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  • Can this code be further optimized??

    - by kaki
    i understand that the code given below will not be compltely understood unless i explain my whole of previous and next lines of code. But this is part of the code which is causing so much of delay in my project and want to optimize this. i want to know which code part is faulty and how could this be replaced. i guess,few can say that use of this function is heavy compared and other ligher method are available to do this work please help, thanks in advance for i in range(len(lists)): save=database_index[lists[i]] #print save #if save[1]!='text0194'and save[1]!='text0526': using_data[save[0]]=save p=os.path.join("c:/begpython/wavnk/",str(str(str(save[1]).replace('phone','text'))+'.pm')) x1=open(p , 'r') x2=open(p ,'r') for i in range(6): x1.readline() x2.readline() gen = (float(line.partition(' ')[0]) for line in x1) r= min(enumerate(gen), key=lambda x: abs(x[1] - float(save[4]))) #print r[0] a1=linecache.getline(str(str(p).replace('.pm','.mcep')), (r[0]+1)) #print a1 p1=str(str(a1).rstrip('\n')).split(' ') #print p1 join_cost_index_end[save[0]]=p1 #print join_cost_index_end gen = (float(line.partition(' ')[0]) for line in x2) r= min(enumerate(gen), key=lambda x: abs(x[1] - float(save[3]))) #print r[0] a2=linecache.getline(str(str(p).replace('.pm','.mcep')), (r[0]+1)) #print a2 p2=str(str(a2).rstrip('\n')).split(' ') #print p2 join_cost_index_strt[save[0]]=p2 #print join_cost_index_strt j=j+1 #print j #print join_cost_index_end #print join_cost_index_strt enter code here here my database_index has about 2,50,000 entries`

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  • python histogram one-liner

    - by mykhal
    there are many ways, how to code histogram in Python. by histogram, i mean function, counting objects in an interable, resulting in the count table (i.e. dict). e.g.: >>> L = 'abracadabra' >>> histogram(L) {'a': 5, 'b': 2, 'c': 1, 'd': 1, 'r': 2} it can be written like this: def histogram(L): d = {} for x in L: if x in d: d[x] += 1 else: d[x] = 1 return d ..however, there are much less ways, how do this in a single expression. if we had "dict comprehensions" in python, we would write: >>> { x: L.count(x) for x in set(L) } but we don't have them, so we have to write: >>> dict([(x, L.count(x)) for x in set(L)]) however, this approach may yet be readable, but is not efficient - L is walked-through multiple times, so this won't work for single-life generators.. the function should iterate well also through gen(), where: def gen(): for x in L: yield x we can go with reduce (R.I.P.): >>> reduce(lambda d,x: dict(d, x=d.get(x,0)+1), L, {}) # wrong! oops, does not work, the key name is 'x', not x :( i ended with: >>> reduce(lambda d,x: dict(d.items() + [(x, d.get(x, 0)+1)]), L, {}) (in py3k, we would have to write list(d.items()) instead of d.items(), but it's hypothethical, since there is no reduce there) please beat me with a better one-liner, more readable! ;)

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  • C# reflection instantiation

    - by NickLarsen
    I am currently trying to create a generic instance factory for which takes an interface as the generic parameter (enforced in the constructor) and then lets you get instantiated objects which implement that interface from all types in all loaded assemblies. The current implementation is as follows:     public class InstantiationFactory     {         protected Type Type { get; set; }         public InstantiationFactory()         {             this.Type = typeof(T);             if (!this.Type.IsInterface)             {                 // is there a more descriptive exception to throw?                 throw new ArgumentException(/* Crafty message */);             }         }         public IEnumerable GetLoadedTypes()         {             // this line of code found in other stack overflow questions             var types = AppDomain.CurrentDomain.GetAssemblies()                 .SelectMany(a = a.GetTypes())                 .Where(/* lambda to identify instantiable types which implement this interface */);             return types;         }         public IEnumerable GetImplementations(IEnumerable types)         {             var implementations = types.Where(/* lambda to identify instantiable types which implement this interface */                 .Select(x = CreateInstance(x));             return implementations;         }         public IEnumerable GetLoadedImplementations()         {             var loadedTypes = GetLoadedTypes();             var implementations = GetImplementations(loadedTypes);             return implementations;         }         private T CreateInstance(Type type)         {             T instance = default(T);             var constructor = type.GetConstructor(Type.EmptyTypes);             if (/* valid to instantiate test */)             {                 object constructed = constructor.Invoke(null);                 instance = (T)constructed;             }             return instance;         }     } It seems useful to me to have my CreateInstance(Type) function implemented as an extension method so I can reuse it later and simplify the code of my factory, but I can't figure out how to return a strongly typed value from that extension method. I realize I could just return an object:     public static class TypeExtensions     {         public object CreateInstance(this Type type)         {             var constructor = type.GetConstructor(Type.EmptyTypes);             return /* valid to instantiate test */ ? constructor.Invoke(null) : null;         }     } Is it possible to have an extension method create a signature per instance of the type it extends? My perfect code would be this, which avoids having to cast the result of the call to CreateInstance():     Type type = typeof(MyParameterlessConstructorImplementingType);     MyParameterlessConstructorImplementingType usable = type.CreateInstance();

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  • Methods and properties in scheme - is object oriented programming possible in scheme?

    - by incrediman
    I will use a simple example to illustrate my question. In Java, C, or any other OOP language, I could create a pie class in a way similar to this: class Apple{ public String flavor; public int pieces; private int tastiness; public goodness(){ return tastiness*pieces; } } What's the best way to do that with Scheme? I suppose I could do with something like this: (define make-pie (lambda (flavor pieces tastiness) (list flavor pieces tastiness))) (define pie-goodness (lambda (pie) (* (list-ref pie 1) (list-ref pie 2)))) (pie-goodness (make-pie 'cherry 2 5)) ;output: 10 ...where cherry is the flavor, 2 is the pieces, and 5 is the tastiness. However then there's no type-safety or visibility, and everything's just shoved in an unlabeled list. How can I improve that? Sidenote: The make-pie procedure expects 3 arguments. If I want to make some of them optional (like I'd be able to in curly-brace languages like Java or C), is it good practice to just take the arguments in as a list (that is treat the arguments as a list - not require one argument which is a list) and deal with them that way?

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  • Return Double from Boost thread

    - by Benedikt Wutzi
    Hi I have an Boost thread which should return a double. The function looks like this: void analyser::findup(const double startwl, const double max, double &myret){ this->data.begin(); for(int i = (int)data.size() ; i >= 0;i--){ if(this->data[i].lambda > startwl){ if(this->data[i].db >= (max-30)) { myret = this->data[i+1].lambda; std::cout <<"in thread " << myret << std::endl; return; } } } } this function is called by another function: void analyser::start_find_up(const double startwl, const double max){ double tmp = -42.0; boost::thread up(&analyser::findup,*this, startwl,max,tmp); std::cout << "before join " << tmp << std::endl; up.join(); std::cout << "after join " << tmp << std::endl; } Anyway I've tried and googled almost anything but i can't get it to return a value. The output looks like this right now. before join -42 in thread 843.487 after join -42 Thanks for any help.

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  • Dynamic Method Creation

    - by TJMonk15
    So, I have been trying to research this all morning, and have had no luck. I am trying to find a way to dynamically create a method/delegate/lambda that returns a new instance of a certain class (not known until runtime) that inherits from a certain base class. I can guarantee the following about the unknown/dynamic class It will always inherit from one known Class (Row) It will have atleast 2 constructors (one accepting a long, and one accepting an IDataRecord) I plan on doign the following: Finding all classes that have a certain attribute on them Creating a delegate/method/lambda/whatever that creates a new instance of the class Storing the delegate/whatever along with some properties in a struct/class Insert the struct into a hashtable When needed, pull the info out of the hashtable and calling the delegate/whatever to get a new instance of the class and returning it/adding it to a list/etc. I need help only with #2 above!!! I have no idea where to start. I really just need some reference material to get me started, or some keywords to throw into google. This is for a compact/simple to use ORM for our office here. I understand the above is not simple, but once working, should make maintaining the code incredibly simple. Please let me know if you need any more info! And thanks in advance! :)

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  • Django repeating vars/cache issue?

    - by Mark
    I'm trying to build a better/more powerful form class for Django. It's working well, except for these sub-forms. Actually, it works perfectly right after I re-start apache, but after I refresh the page a few times, my HTML output starts to look like this: <input class="text" type="text" id="pickup_addr-pickup_addr-pickup_addr-id-pickup_addr-venue" value="" name="pickup_addr-pickup_addr-pickup_addr-pickup_addr-venue" /> The pickup_addr- part starts repeating many times. I was looking for loops around the prefix code that might have cause this to happen, but the output isn't even consistent when I refresh the page, so I think something is getting cached somewhere, but I can't even imagine how that's possible. The prefix car should be reset when the class is initialized, no? Unless it's somehow not initializing something? class Form(object): count = 0 def __init__(self, data={}, prefix='', action='', id=None, multiple=False): self.fields = {} self.subforms = {} self.data = {} self.action = action self.id = fnn(id, 'form%d' % Form.count) self.errors = [] self.valid = True if not empty(prefix) and prefix[-1:] not in ('-','_'): prefix += '-' for name, field in inspect.getmembers(self, lambda m: isinstance(m, Field)): if name[:2] == '__': continue field_name = fnn(field.name, name) field.label = fnn(field.label, humanize(field_name)) field.name = field.widget.name = prefix + field_name + ife(multiple, '[]') field.id = field.auto_id = field.widget.id = ife(field.id==None, 'id-') + prefix + fnn(field.id, field_name) + ife(multiple, Form.count) field.errors = [] val = fnn(field.widget.get_value(data), field.default) if isinstance(val, basestring): try: val = field.coerce(field.format(val)) except Exception, err: self.valid = False field.errors.append(escape_html(err)) field.val = self.data[name] = field.widget.val = val for rule in field.rules: rule.fields = self.fields rule.val = field.val rule.name = field.name self.fields[name] = field for name, form in inspect.getmembers(self, lambda m: ispropersubclass(m, Form)): if name[:2] == '__': continue self.subforms[name] = self.__dict__[name] = form(data=data, prefix='%s%s-' % (prefix, name)) Form.count += 1 Let me know if you need more code... I know it's a lot, but I just can't figure out what's causing this!

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  • Help me write my LISP :) LISP environments, Ruby Hashes...

    - by MikeC8
    I'm implementing a rudimentary version of LISP in Ruby just in order to familiarize myself with some concepts. I'm basing my implementation off of Peter Norvig's Lispy (http://norvig.com/lispy.html). There's something I'm missing here though, and I'd appreciate some help... He subclasses Python's dict as follows: class Env(dict): "An environment: a dict of {'var':val} pairs, with an outer Env." def __init__(self, parms=(), args=(), outer=None): self.update(zip(parms,args)) self.outer = outer def find(self, var): "Find the innermost Env where var appears." return self if var in self else self.outer.find(var) He then goes on to explain why he does this rather than just using a dict. However, for some reason, his explanation keeps passing in through my eyes and out through the back of my head. Why not use a dict, and then inside the eval function, when a new "sub-environment" needs to be created, just take the existing dict and update the key/value pairs that need to be updated, and pass that new dict into the next eval? Won't the Python interpreter keep track of the previous "outer" envs? And won't the nature of the recursion ensure that the values are pulled out from "inner" to "outer"? I'm using Ruby, and I tried to implement things this way. Something's not working though, and it might be because of this, or perhaps not. Here's my eval function, env being a regular Hash: def eval(x, env = $global_env) ........ elsif x[0] == "lambda" then ->(*args) { eval(x[2], env.merge(Hash[*x[1].zip(args).flatten(1)])) } ........ end The line that matters of course is the "lambda" one. If there is a difference, what's importantly different between what I'm doing here and what Norvig did with his Env class? If there's no difference, then perhaps someone can enlighten me as to why Norvig uses the Env class. Thanks :)

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  • emacs lisp mapcar doesn't apply function to all elements?

    - by Stephen
    Hi, I have a function that takes a list and replaces some elements. I have constructed it as a closure so that the free variable cannot be modified outside of the function. (defun transform (elems) (lexical-let ( (elems elems) ) (lambda (seq) (let (e) (while (setq e (car elems)) (setf (nth e seq) e) (setq elems (cdr elems))) seq)))) I call this on a list of lists. (defun tester (seq-list) (let ( (elems '(1 3 5)) ) (mapcar (transform elems) seq-list))) => ((10 1 8 3 6 5 4 3 2 1) ("a" "b" "c" "d" "e" "f")) It does not seem to apply the function to the second element of the list provided to tester(). However, if I explicitly apply this function to the individual elements, it works... (defun tester (seq-list) (let ( (elems '(1 3 5)) ) (list (funcall (transform elems) (car seq-list)) (funcall (transform elems) (cadr seq-list))))) => ((10 1 8 3 6 5 4 3 2 1) ("a" 1 "c" 3 "e" 5)) If I write a simple function using the same concepts as above, mapcar seems to work... What could I be doing wrong? (defun transform (x) (lexical-let ( (x x) ) (lambda (y) (+ x y)))) (defun tester (seq) (let ( (x 1) ) (mapcar (transform x) seq))) (tester (list 1 3)) => (2 4) Thanks

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  • Problem with circular definition in Scheme

    - by user8472
    I am currently working through SICP using Guile as my primary language for the exercises. I have found a strange behavior while implementing the exercises in chapter 3.5. I have reproduced this behavior using Guile 1.4, Guile 1.8.6 and Guile 1.8.7 on a variety of platforms and am certain it is not specific to my setup. This code works fine (and computes e): (define y (integral (delay dy) 1 0.001)) (define dy (stream-map (lambda (x) x) y)) (stream-ref y 1000) The following code should give an identical result: (define (solve f y0 dt) (define y (integral (delay dy) y0 dt)) (define dy (stream-map f y)) y) (solve (lambda (x) x) 1 0.001) But it yields the error message: standard input:7:14: While evaluating arguments to stream-map in expression (stream-map f y): standard input:7:14: Unbound variable: y ABORT: (unbound-variable) So when embedded in a procedure definition, the (define y ...) does not work, whereas outside the procedure in the global environment at the REPL it works fine. What am I doing wrong here? I can post the auxiliary code (i.e., the definitions of integral, stream-map etc.) if necessary, too. With the exception of the system-dependent code for cons-stream, they are all in the book. My own implementation of cons-stream for Guile is as follows: (define-macro (cons-stream a b) `(cons ,a (delay ,b)))

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  • Macro and array crossing

    - by Thomas
    I am having a problem with a lisp macro. I would like to create a macro which generate a switch case according to an array. Here is the code to generate the switch-case: (defun split-elem(val) `(,(car val) ',(cdr val))) (defmacro generate-switch-case (var opts) `(case ,var ,(mapcar #'split-elem opts))) I can use it with a code like this: (generate-switch-case onevar ((a . A) (b . B))) But when I try to do something like this: (defparameter *operators* '((+ . OPERATOR-PLUS) (- . OPERATOR-MINUS) (/ . OPERATOR-DIVIDE) (= . OPERATOR-EQUAL) (* . OPERATOR-MULT))) (defmacro tokenize (data ops) (let ((sym (string->list data))) (mapcan (lambda (x) (generate-switch-case x ops)) sym))) (tokenize data *operators*) I got this error: *** - MAPCAR: A proper list must not end with OPS. But I don't understand why. When I print the type of ops I get SYMBOL I was expecting CONS, is it related? Also, for my function tokenize how many times the lambda is evaluated (or the macro expanded)?

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  • Conversion from C code to CudaC code I get unpredictable results

    - by Abhi
    include include include include define pi 3.14159265359 lo*lo*p-2*mu,freq=2.25*1e6,wavelength=(long double)lo/freq,dh=(long double)wavelength/ 30.0,dt=(long double)dh/(lo*1.5); (1000*dh)); (p*dh),lambdaplus2mudtbydh=(lambda+2*mu)*dt/dh,lambdadtbydh=lambda*dt/dh,dtmubydh=dt*mu/ dh; double**U,long double**V){ for(int k=0,l=0;k<=yno-1 && l<=yno;k++,l++){ U[i+1][l]+=dtbyrhodh*(X[i+1][l+1]-X[i+1][l]+Z[i+1][l]- Z[i][l]); [k+1]-Y[j][k+1]); } double**U,long double**V){ for(int k=0,l=0;k<=yno-1 && l<=yno;k++,l++){ U[i+1][k])+lambdadtbydh*(V[i+1][k+1]-V[i][k+1]); V[i][k+1])+lambdadtbydh*(U[i+1][k+1]-U[i+1][k]); U[j][l]); int main(){ clock_t start,end; long double time_taken; start=clock(); long double **X,**Y,**U,**V,**Z;int n=1; X=Make2DDoubleArray(xno+2,yno+2); Y=Make2DDoubleArray(xno+2,yno+2); Z=Make2DDoubleArray(xno+1,yno+1); U=Make2DDoubleArray(xno+2,yno+2); V=Make2DDoubleArray(xno+2,yno+2); for (n=1;n<=timesteps;n++){ } end=clock(); time_taken=(long double)(end-start)/CLOCKS_PER_SEC; printf("Time elapsed is %Lf\nGRID Size:%Lf*%Lf\nTime Steps Taken:%d\n",time_taken,(xno),floor(yno),n); return 0; }

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  • Is There a Better Way to Feed Different Parameters into Functions with If-Statements?

    - by FlowofSoul
    I've been teaching myself Python for a little while now, and I've never programmed before. I just wrote a basic backup program that writes out the progress of each individual file while it is copying. I wrote a function that determines buffer size so that smaller files are copied with a smaller buffer, and bigger files are copied with a bigger buffer. The way I have the code set up now doesn't seem very efficient, as there is an if loop that then leads to another if loops, creating four options, and they all just call the same function with different parameters. import os import sys def smartcopy(filestocopy, dest_path, show_progress = False): """Determines what buffer size to use with copy() Setting show_progress to True calls back display_progress()""" #filestocopy is a list of dictionaries for the files needed to be copied #dictionaries are used as the fullpath, st_mtime, and size are needed if len(filestocopy.keys()) == 0: return None #Determines average file size for which buffer to use average_size = 0 for key in filestocopy.keys(): average_size += int(filestocopy[key]['size']) average_size = average_size/len(filestocopy.keys()) #Smaller buffer for smaller files if average_size < 1024*10000: #Buffer sizes determined by informal tests on my laptop if show_progress: for key in filestocopy.keys(): #dest_path+key is the destination path, as the key is the relative path #and the dest_path is the top level folder copy(filestocopy[key]['fullpath'], dest_path+key, callback = lambda pos, total: display_progress(pos, total, key)) else: for key in filestocopy.keys(): copy(filestocopy[key]['fullpath'], dest_path+key, callback = None) #Bigger buffer for bigger files else: if show_progress: for key in filestocopy.keys(): copy(filestocopy[key]['fullpath'], dest_path+key, 1024*2600, callback = lambda pos, total: display_progress(pos, total, key)) else: for key in filestocopy.keys(): copy(filestocopy[key]['fullpath'], dest_path+key, 1024*2600) def display_progress(pos, total, filename): percent = round(float(pos)/float(total)*100,2) if percent <= 100: sys.stdout.write(filename + ' - ' + str(percent)+'% \r') else: percent = 100 sys.stdout.write(filename + ' - Completed \n') Is there a better way to accomplish what I'm doing? Sorry if the code is commented poorly or hard to follow. I didn't want to ask someone to read through all 120 lines of my poorly written code, so I just isolated the two functions. Thanks for any help.

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  • scheme basic loop

    - by utku
    I'm trying to write a scheme func that behaves in a way similar to a loop. (loop min max func) This loop should perform the func between the range min and max (integers) -- one of an example like this (loop 3 6 (lambda (x) (display (* x x)) (newline))) 9 16 25 36 and I define the function as ( define ( loop min max fn) (cond ((>= max min) ( ( fn min ) ( loop (+ min 1 ) max fn) ) ) ) ) when I run the code I get the result then an error occur. I couldn't handle this error. (loop 3 6 (lambda (x) (display(* x x))(newline))) 9 16 25 36 Backtrace: In standard input: 41: 0* [loop 3 6 #] In utku1.scheme: 9: 1 (cond ((= max min) ((fn min) (loop # max fn)))) 10: 2 [# ... 10: 3* [loop 4 6 #] 9: 4 (cond ((= max min) ((fn min) (loop # max fn)))) 10: 5 [# ... 10: 6* [loop 5 6 #] 9: 7 (cond ((= max min) ((fn min) (loop # max fn)))) 10: 8 [# ... 10: 9* [loop 6 6 #] 9: 10 (cond ((= max min) ((fn min) (loop # max fn)))) 10: 11 [# #] utku1.scheme:10:31: In expression ((fn min) (loop # max ...)): utku1.scheme:10:31: Wrong type to apply: #<unspecified> ABORT: (misc-error)

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  • In C/C++ mode in Emacs, change face of code in #if 0...#endif block to comment face

    - by pogopop77
    I'm trying to add functionality found in some other code editors to my Emacs configuration, whereby C/C++ code within #if 0...#endif blocks is automatically set to the comment face/font. Based on my testing, cpp-highlight-mode does something like what I want, but requires user action. It seems like tying into the font-lock functionality is the correct option to make the behavior automatic. I have successfully followed examples in the GNU documentation to change the face of single-line regular expressions. For example: (add-hook 'c-mode-common-hook (lambda () (font-lock-add-keywords nil '(("\\<\\(FIXME\\|TODO\\|HACK\\|fixme\\|todo\\|hack\\)" 1 font-lock-warning-face t))))) works fine to highlight debug related keywords anywhere in a file. However, I am having problems matching #if 0...#endif as a multiline regular expression. I found some useful information in this post (How to compose region like ""), that suggested that Emacs must be told specifically to allow for multiline matches. But this code: (add-hook 'c-mode-common-hook (lambda () '(progn (setq font-lock-multiline t) (font-lock-add-keywords nil '(("#if 0\\(.\\|\n\\)*?#endif" 1 font-lock-comment-face t)))))) still does not work for me. Perhaps my regular expression is wrong (though it appears to work using M-x re-builder), I've messed up my syntax, or I'm following the wrong approach entirely. I'm using Aquamacs 2.1 (which is based on GNU Emacs 23.2.50.1) on OS X 10.6.5, if that makes a difference. Any assistance would be appreciated!

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  • Rails nested attributes with a join model, where one of the models being joined is a new record

    - by gzuki
    I'm trying to build a grid, in rails, for entering data. It has rows and columns, and rows and columns are joined by cells. In my view, I need for the grid to be able to handle having 'new' rows and columns on the edge, so that if you type in them and then submit, they are automatically generated, and their shared cells are connected to them correctly. I want to be able to do this without JS. Rails nested attributes fail to handle being mapped to both a new record and a new column, they can only do one or the other. The reason is that they are a nested specifically in one of the two models, and whichever one they aren't nested in will have no id (since it doesn't exist yet), and when pushed through accepts_nested_attributes_for on the top level Grid model, they will only be bound to the new object created for whatever they were nested in. How can I handle this? Do I have to override rails handling of nested attributes? My models look like this, btw: class Grid < ActiveRecord::Base has_many :rows has_many :columns has_many :cells, :through => :rows accepts_nested_attributes_for :rows, :allow_destroy => true, :reject_if => lambda {|a| a[:description].blank? } accepts_nested_attributes_for :columns, :allow_destroy => true, :reject_if => lambda {|a| a[:description].blank? } end class Column < ActiveRecord::Base belongs_to :grid has_many :cells, :dependent => :destroy has_many :rows, :through => :grid end class Row < ActiveRecord::Base belongs_to :grid has_many :cells, :dependent => :destroy has_many :columns, :through => :grid accepts_nested_attributes_for :cells end class Cell < ActiveRecord::Base belongs_to :row belongs_to :column has_one :grid, :through => :row end

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  • Permuting output of a tree of closures

    - by yan
    This a conceptual question on how one would implement the following in Lisp (assuming Common Lisp in my case, but any dialect would work). Assume you have a function that creates closures that sequentially iterate over an arbitrary collection (or otherwise return different values) of data and returns nil when exhausted, i.e. (defun make-counter (up-to) (let ((cnt 0)) (lambda () (if (< cnt up-to) (incf cnt) nil)))) CL-USER> (defvar gen (make-counter 3)) GEN CL-USER> (funcall gen) 1 CL-USER> (funcall gen) 2 CL-USER> (funcall gen) 3 CL-USER> (funcall gen) NIL CL-USER> (funcall gen) NIL Now, assume you are trying to permute a combinations of one or more of these closures. How would you implement a function that returns a new closure that subsequently creates a permutation of all closures contained within it? i.e.: (defun permute-closures (counters) ......) such that the following holds true: CL-USER> (defvar collection (permute-closures (list (make-counter 3) (make-counter 3)))) CL-USER> (funcall collection) (1 1) CL-USER> (funcall collection) (1 2) CL-USER> (funcall collection) (1 3) CL-USER> (funcall collection) (2 1) ... and so on. The way I had it designed originally was to add a 'pause' parameter to the initial counting lambda such that when iterating you can still call it and receive the old cached value if passed ":pause t", in hopes of making the permutation slightly cleaner. Also, while the example above is a simple list of two identical closures, the list can be an arbitrarily-complicated tree (which can be permuted in depth-first order, and the resulting permutation set would have the shape of the tree.). I had this implemented, but my solution wasn't very clean and am trying to poll how others would approach the problem. Thanks in advance.

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  • How can I bind the second argument in a function but not the first (in an elegant way)?

    - by Frank Osterfeld
    Is there a way in Haskell to bind the second argument but not the first of a function without using lambda functions or defining another "local" function? Example. I have a binary function like: sub :: Int -> Int -> Int sub x y = x - y Now if I want to bind the first argument, I can do so easily using (sub someExpression): mapSubFrom5 x = map (sub 5) x *Main> mapSubFrom5 [1,2,3,4,5] [4,3,2,1,0] That works fine if I want to bind the first n arguments without "gap". If I want to bind the second argument but not the first, the two options I am aware of are more verbose: Either via another, local, function: mapSub5 x = map sub5 x where sub5 x = sub x 5 *Main> mapSub5 [1,2,3,4,5] [-4,-3,-2,-1,0] Or using lambda: mapSub5 x = map (\x -> sub x 5) x While both are working fine, I like the elegance of "sub 5" and wonder if there is a similarly elegant way to bind the n-th (n 1) argument of a function?

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  • Understanding C# async / await (1) Compilation

    - by Dixin
    Now the async / await keywords are in C#. Just like the async and ! in F#, this new C# feature provides great convenience. There are many nice documents talking about how to use async / await in specific scenarios, like using async methods in ASP.NET 4.5 and in ASP.NET MVC 4, etc. In this article we will look at the real code working behind the syntax sugar. According to MSDN: The async modifier indicates that the method, lambda expression, or anonymous method that it modifies is asynchronous. Since lambda expression / anonymous method will be compiled to normal method, we will focus on normal async method. Preparation First of all, Some helper methods need to make up. internal class HelperMethods { internal static int Method(int arg0, int arg1) { // Do some IO. WebClient client = new WebClient(); Enumerable.Repeat("http://weblogs.asp.net/dixin", 10) .Select(client.DownloadString).ToArray(); int result = arg0 + arg1; return result; } internal static Task<int> MethodTask(int arg0, int arg1) { Task<int> task = new Task<int>(() => Method(arg0, arg1)); task.Start(); // Hot task (started task) should always be returned. return task; } internal static void Before() { } internal static void Continuation1(int arg) { } internal static void Continuation2(int arg) { } } Here Method() is a long running method doing some IO. Then MethodTask() wraps it into a Task and return that Task. Nothing special here. Await something in async method Since MethodTask() returns Task, let’s try to await it: internal class AsyncMethods { internal static async Task<int> MethodAsync(int arg0, int arg1) { int result = await HelperMethods.MethodTask(arg0, arg1); return result; } } Because we used await in the method, async must be put on the method. Now we get the first async method. According to the naming convenience, it is named MethodAsync. Of course a async method can be awaited. So we have a CallMethodAsync() to call MethodAsync(): internal class AsyncMethods { internal static async Task<int> CallMethodAsync(int arg0, int arg1) { int result = await MethodAsync(arg0, arg1); return result; } } After compilation, MethodAsync() and CallMethodAsync() becomes the same logic. This is the code of MethodAsyc(): internal class CompiledAsyncMethods { [DebuggerStepThrough] [AsyncStateMachine(typeof(MethodAsyncStateMachine))] // async internal static /*async*/ Task<int> MethodAsync(int arg0, int arg1) { MethodAsyncStateMachine methodAsyncStateMachine = new MethodAsyncStateMachine() { Arg0 = arg0, Arg1 = arg1, Builder = AsyncTaskMethodBuilder<int>.Create(), State = -1 }; methodAsyncStateMachine.Builder.Start(ref methodAsyncStateMachine); return methodAsyncStateMachine.Builder.Task; } } It just creates and starts a state machine, MethodAsyncStateMachine: [CompilerGenerated] [StructLayout(LayoutKind.Auto)] internal struct MethodAsyncStateMachine : IAsyncStateMachine { public int State; public AsyncTaskMethodBuilder<int> Builder; public int Arg0; public int Arg1; public int Result; private TaskAwaiter<int> awaitor; void IAsyncStateMachine.MoveNext() { try { if (this.State != 0) { this.awaitor = HelperMethods.MethodTask(this.Arg0, this.Arg1).GetAwaiter(); if (!this.awaitor.IsCompleted) { this.State = 0; this.Builder.AwaitUnsafeOnCompleted(ref this.awaitor, ref this); return; } } else { this.State = -1; } this.Result = this.awaitor.GetResult(); } catch (Exception exception) { this.State = -2; this.Builder.SetException(exception); return; } this.State = -2; this.Builder.SetResult(this.Result); } [DebuggerHidden] void IAsyncStateMachine.SetStateMachine(IAsyncStateMachine param0) { this.Builder.SetStateMachine(param0); } } The generated code has been refactored, so it is readable and can be compiled. Several things can be observed here: The async modifier is gone, which shows, unlike other modifiers (e.g. static), there is no such IL/CLR level “async” stuff. It becomes a AsyncStateMachineAttribute. This is similar to the compilation of extension method. The generated state machine is very similar to the state machine of C# yield syntax sugar. The local variables (arg0, arg1, result) are compiled to fields of the state machine. The real code (await HelperMethods.MethodTask(arg0, arg1)) is compiled into MoveNext(): HelperMethods.MethodTask(this.Arg0, this.Arg1).GetAwaiter(). CallMethodAsync() will create and start its own state machine CallMethodAsyncStateMachine: internal class CompiledAsyncMethods { [DebuggerStepThrough] [AsyncStateMachine(typeof(CallMethodAsyncStateMachine))] // async internal static /*async*/ Task<int> CallMethodAsync(int arg0, int arg1) { CallMethodAsyncStateMachine callMethodAsyncStateMachine = new CallMethodAsyncStateMachine() { Arg0 = arg0, Arg1 = arg1, Builder = AsyncTaskMethodBuilder<int>.Create(), State = -1 }; callMethodAsyncStateMachine.Builder.Start(ref callMethodAsyncStateMachine); return callMethodAsyncStateMachine.Builder.Task; } } CallMethodAsyncStateMachine has the same logic as MethodAsyncStateMachine above. The detail of the state machine will be discussed soon. Now it is clear that: async /await is a C# language level syntax sugar. There is no difference to await a async method or a normal method. As long as a method returns Task, it is awaitable. State machine and continuation To demonstrate more details in the state machine, a more complex method is created: internal class AsyncMethods { internal static async Task<int> MultiCallMethodAsync(int arg0, int arg1, int arg2, int arg3) { HelperMethods.Before(); int resultOfAwait1 = await MethodAsync(arg0, arg1); HelperMethods.Continuation1(resultOfAwait1); int resultOfAwait2 = await MethodAsync(arg2, arg3); HelperMethods.Continuation2(resultOfAwait2); int resultToReturn = resultOfAwait1 + resultOfAwait2; return resultToReturn; } } In this method: There are multiple awaits. There are code before the awaits, and continuation code after each await After compilation, this multi-await method becomes the same as above single-await methods: internal class CompiledAsyncMethods { [DebuggerStepThrough] [AsyncStateMachine(typeof(MultiCallMethodAsyncStateMachine))] // async internal static /*async*/ Task<int> MultiCallMethodAsync(int arg0, int arg1, int arg2, int arg3) { MultiCallMethodAsyncStateMachine multiCallMethodAsyncStateMachine = new MultiCallMethodAsyncStateMachine() { Arg0 = arg0, Arg1 = arg1, Arg2 = arg2, Arg3 = arg3, Builder = AsyncTaskMethodBuilder<int>.Create(), State = -1 }; multiCallMethodAsyncStateMachine.Builder.Start(ref multiCallMethodAsyncStateMachine); return multiCallMethodAsyncStateMachine.Builder.Task; } } It creates and starts one single state machine, MultiCallMethodAsyncStateMachine: [CompilerGenerated] [StructLayout(LayoutKind.Auto)] internal struct MultiCallMethodAsyncStateMachine : IAsyncStateMachine { public int State; public AsyncTaskMethodBuilder<int> Builder; public int Arg0; public int Arg1; public int Arg2; public int Arg3; public int ResultOfAwait1; public int ResultOfAwait2; public int ResultToReturn; private TaskAwaiter<int> awaiter; void IAsyncStateMachine.MoveNext() { try { switch (this.State) { case -1: HelperMethods.Before(); this.awaiter = AsyncMethods.MethodAsync(this.Arg0, this.Arg1).GetAwaiter(); if (!this.awaiter.IsCompleted) { this.State = 0; this.Builder.AwaitUnsafeOnCompleted(ref this.awaiter, ref this); } break; case 0: this.ResultOfAwait1 = this.awaiter.GetResult(); HelperMethods.Continuation1(this.ResultOfAwait1); this.awaiter = AsyncMethods.MethodAsync(this.Arg2, this.Arg3).GetAwaiter(); if (!this.awaiter.IsCompleted) { this.State = 1; this.Builder.AwaitUnsafeOnCompleted(ref this.awaiter, ref this); } break; case 1: this.ResultOfAwait2 = this.awaiter.GetResult(); HelperMethods.Continuation2(this.ResultOfAwait2); this.ResultToReturn = this.ResultOfAwait1 + this.ResultOfAwait2; this.State = -2; this.Builder.SetResult(this.ResultToReturn); break; } } catch (Exception exception) { this.State = -2; this.Builder.SetException(exception); } } [DebuggerHidden] void IAsyncStateMachine.SetStateMachine(IAsyncStateMachine stateMachine) { this.Builder.SetStateMachine(stateMachine); } } Once again, the above state machine code is already refactored, but it still has a lot of things. More clean up can be done if we only keep the core logic, and the state machine can become very simple: [CompilerGenerated] [StructLayout(LayoutKind.Auto)] internal struct MultiCallMethodAsyncStateMachine : IAsyncStateMachine { // State: // -1: Begin // 0: 1st await is done // 1: 2nd await is done // ... // -2: End public int State; public TaskCompletionSource<int> ResultToReturn; // int resultToReturn ... public int Arg0; // int Arg0 public int Arg1; // int arg1 public int Arg2; // int arg2 public int Arg3; // int arg3 public int ResultOfAwait1; // int resultOfAwait1 ... public int ResultOfAwait2; // int resultOfAwait2 ... private Task<int> currentTaskToAwait; /// <summary> /// Moves the state machine to its next state. /// </summary> public void MoveNext() // IAsyncStateMachine member. { try { switch (this.State) { // Original code is split by "await"s into "case"s: // case -1: // HelperMethods.Before(); // MethodAsync(Arg0, arg1); // case 0: // int resultOfAwait1 = await ... // HelperMethods.Continuation1(resultOfAwait1); // MethodAsync(arg2, arg3); // case 1: // int resultOfAwait2 = await ... // HelperMethods.Continuation2(resultOfAwait2); // int resultToReturn = resultOfAwait1 + resultOfAwait2; // return resultToReturn; case -1: // -1 is begin. HelperMethods.Before(); // Code before 1st await. this.currentTaskToAwait = AsyncMethods.MethodAsync(this.Arg0, this.Arg1); // 1st task to await // When this.currentTaskToAwait is done, run this.MoveNext() and go to case 0. this.State = 0; MultiCallMethodAsyncStateMachine that1 = this; // Cannot use "this" in lambda so create a local variable. this.currentTaskToAwait.ContinueWith(_ => that1.MoveNext()); break; case 0: // Now 1st await is done. this.ResultOfAwait1 = this.currentTaskToAwait.Result; // Get 1st await's result. HelperMethods.Continuation1(this.ResultOfAwait1); // Code after 1st await and before 2nd await. this.currentTaskToAwait = AsyncMethods.MethodAsync(this.Arg2, this.Arg3); // 2nd task to await // When this.currentTaskToAwait is done, run this.MoveNext() and go to case 1. this.State = 1; MultiCallMethodAsyncStateMachine that2 = this; this.currentTaskToAwait.ContinueWith(_ => that2.MoveNext()); break; case 1: // Now 2nd await is done. this.ResultOfAwait2 = this.currentTaskToAwait.Result; // Get 2nd await's result. HelperMethods.Continuation2(this.ResultOfAwait2); // Code after 2nd await. int resultToReturn = this.ResultOfAwait1 + this.ResultOfAwait2; // Code after 2nd await. // End with resultToReturn. this.State = -2; // -2 is end. this.ResultToReturn.SetResult(resultToReturn); break; } } catch (Exception exception) { // End with exception. this.State = -2; // -2 is end. this.ResultToReturn.SetException(exception); } } /// <summary> /// Configures the state machine with a heap-allocated replica. /// </summary> /// <param name="stateMachine">The heap-allocated replica.</param> [DebuggerHidden] public void SetStateMachine(IAsyncStateMachine stateMachine) // IAsyncStateMachine member. { // No core logic. } } Only Task and TaskCompletionSource are involved in this version. And MultiCallMethodAsync() can be simplified to: [DebuggerStepThrough] [AsyncStateMachine(typeof(MultiCallMethodAsyncStateMachine))] // async internal static /*async*/ Task<int> MultiCallMethodAsync(int arg0, int arg1, int arg2, int arg3) { MultiCallMethodAsyncStateMachine multiCallMethodAsyncStateMachine = new MultiCallMethodAsyncStateMachine() { Arg0 = arg0, Arg1 = arg1, Arg2 = arg2, Arg3 = arg3, ResultToReturn = new TaskCompletionSource<int>(), // -1: Begin // 0: 1st await is done // 1: 2nd await is done // ... // -2: End State = -1 }; multiCallMethodAsyncStateMachine.MoveNext(); // Original code are moved into this method. return multiCallMethodAsyncStateMachine.ResultToReturn.Task; } Now the whole state machine becomes very clean - it is about callback: Original code are split into pieces by “await”s, and each piece is put into each “case” in the state machine. Here the 2 awaits split the code into 3 pieces, so there are 3 “case”s. The “piece”s are chained by callback, that is done by Builder.AwaitUnsafeOnCompleted(callback), or currentTaskToAwait.ContinueWith(callback) in the simplified code. A previous “piece” will end with a Task (which is to be awaited), when the task is done, it will callback the next “piece”. The state machine’s state works with the “case”s to ensure the code “piece”s executes one after another. Callback If we focus on the point of callback, the simplification  can go even further – the entire state machine can be completely purged, and we can just keep the code inside MoveNext(). Now MultiCallMethodAsync() becomes: internal static Task<int> MultiCallMethodAsync(int arg0, int arg1, int arg2, int arg3) { TaskCompletionSource<int> taskCompletionSource = new TaskCompletionSource<int>(); try { // Oringinal code begins. HelperMethods.Before(); MethodAsync(arg0, arg1).ContinueWith(await1 => { int resultOfAwait1 = await1.Result; HelperMethods.Continuation1(resultOfAwait1); MethodAsync(arg2, arg3).ContinueWith(await2 => { int resultOfAwait2 = await2.Result; HelperMethods.Continuation2(resultOfAwait2); int resultToReturn = resultOfAwait1 + resultOfAwait2; // Oringinal code ends. taskCompletionSource.SetResult(resultToReturn); }); }); } catch (Exception exception) { taskCompletionSource.SetException(exception); } return taskCompletionSource.Task; } Please compare with the original async / await code: HelperMethods.Before(); int resultOfAwait1 = await MethodAsync(arg0, arg1); HelperMethods.Continuation1(resultOfAwait1); int resultOfAwait2 = await MethodAsync(arg2, arg3); HelperMethods.Continuation2(resultOfAwait2); int resultToReturn = resultOfAwait1 + resultOfAwait2; return resultToReturn; Yeah that is the magic of C# async / await: Await is not to wait. In a await expression, a Task object will be return immediately so that execution is not blocked. The continuation code is compiled as that Task’s callback code. When that task is done, continuation code will execute. Please notice that many details inside the state machine are omitted for simplicity, like context caring, etc. If you want to have a detailed picture, please do check out the source code of AsyncTaskMethodBuilder and TaskAwaiter.

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  • Entity Framework 4.0 and DDD patterns

    - by Voice
    Hi everybody I use EntityFramework as ORM and I have simple POCO Domain Model with two base classes that represent Value Object and Entity Object Patterns (Evans). These two patterns is all about equality of two objects, so I overrode Equals and GetHashCode methods. Here are these two classes: public abstract class EntityObject<T>{ protected T _ID = default(T); public T ID { get { return _ID; } protected set { _ID = value; } } public sealed override bool Equals(object obj) { EntityObject<T> compareTo = obj as EntityObject<T>; return (compareTo != null) && ((HasSameNonDefaultIdAs(compareTo) || (IsTransient && compareTo.IsTransient)) && HasSameBusinessSignatureAs(compareTo)); } public virtual void MakeTransient() { _ID = default(T); } public bool IsTransient { get { return _ID == null || _ID.Equals(default(T)); } } public override int GetHashCode() { if (default(T).Equals(_ID)) return 0; return _ID.GetHashCode(); } private bool HasSameBusinessSignatureAs(EntityObject<T> compareTo) { return ToString().Equals(compareTo.ToString()); } private bool HasSameNonDefaultIdAs(EntityObject<T> compareTo) { return (_ID != null && !_ID.Equals(default(T))) && (compareTo._ID != null && !compareTo._ID.Equals(default(T))) && _ID.Equals(compareTo._ID); } public override string ToString() { StringBuilder str = new StringBuilder(); str.Append(" Class: ").Append(GetType().FullName); if (!IsTransient) str.Append(" ID: " + _ID); return str.ToString(); } } public abstract class ValueObject<T, U> : IEquatable<T> where T : ValueObject<T, U> { private static List<PropertyInfo> Properties { get; set; } private static Func<ValueObject<T, U>, PropertyInfo, object[], object> _GetPropValue; static ValueObject() { Properties = new List<PropertyInfo>(); var propParam = Expression.Parameter(typeof(PropertyInfo), "propParam"); var target = Expression.Parameter(typeof(ValueObject<T, U>), "target"); var indexPar = Expression.Parameter(typeof(object[]), "indexPar"); var call = Expression.Call(propParam, typeof(PropertyInfo).GetMethod("GetValue", new[] { typeof(object), typeof(object[]) }), new[] { target, indexPar }); var lambda = Expression.Lambda<Func<ValueObject<T, U>, PropertyInfo, object[], object>>(call, target, propParam, indexPar); _GetPropValue = lambda.Compile(); } public U ID { get; protected set; } public override Boolean Equals(Object obj) { if (ReferenceEquals(null, obj)) return false; if (obj.GetType() != GetType()) return false; return Equals(obj as T); } public Boolean Equals(T other) { if (ReferenceEquals(null, other)) return false; if (ReferenceEquals(this, other)) return true; foreach (var property in Properties) { var oneValue = _GetPropValue(this, property, null); var otherValue = _GetPropValue(other, property, null); if (null == oneValue && null == otherValue) return false; if (false == oneValue.Equals(otherValue)) return false; } return true; } public override Int32 GetHashCode() { var hashCode = 36; foreach (var property in Properties) { var propertyValue = _GetPropValue(this, property, null); if (null == propertyValue) continue; hashCode = hashCode ^ propertyValue.GetHashCode(); } return hashCode; } public override String ToString() { var stringBuilder = new StringBuilder(); foreach (var property in Properties) { var propertyValue = _GetPropValue(this, property, null); if (null == propertyValue) continue; stringBuilder.Append(propertyValue.ToString()); } return stringBuilder.ToString(); } protected static void RegisterProperty(Expression<Func<T, Object>> expression) { MemberExpression memberExpression; if (ExpressionType.Convert == expression.Body.NodeType) { var body = (UnaryExpression)expression.Body; memberExpression = body.Operand as MemberExpression; } else memberExpression = expression.Body as MemberExpression; if (null == memberExpression) throw new InvalidOperationException("InvalidMemberExpression"); Properties.Add(memberExpression.Member as PropertyInfo); } } Everything was OK until I tried to delete some related objects (aggregate root object with two dependent objects which was marked for cascade deletion): I've got an exception "The relationship could not be changed because one or more of the foreign-key properties is non-nullable". I googled this and found http://blog.abodit.com/2010/05/the-relationship-could-not-be-changed-because-one-or-more-of-the-foreign-key-properties-is-non-nullable/ I changed GetHashCode to base.GetHashCode() and error disappeared. But now it breaks all my code: I can't override GetHashCode for my POCO objects = I can't override Equals = I can't implement Value Object and Entity Object patters for my POCO objects. So, I appreciate any solutions, workarounds here etc.

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  • Where can these be posted besides the Python Cookbook?

    - by Noctis Skytower
    Whitespace Assembler #! /usr/bin/env python """Assembler.py Compiles a program from "Assembly" folder into "Program" folder. Can be executed directly by double-click or on the command line. Give name of *.WSA file without extension (example: stack_calc).""" ################################################################################ __author__ = 'Stephen "Zero" Chappell <[email protected]>' __date__ = '14 March 2010' __version__ = '$Revision: 3 $' ################################################################################ import string from Interpreter import INS, MNEMONIC ################################################################################ def parse(code): program = [] process_virtual(program, code) process_control(program) return tuple(program) def process_virtual(program, code): for line, text in enumerate(code.split('\n')): if not text or text[0] == '#': continue if text.startswith('part '): parse_part(program, line, text[5:]) elif text.startswith(' '): parse_code(program, line, text[5:]) else: syntax_error(line) def syntax_error(line): raise SyntaxError('Line ' + str(line + 1)) ################################################################################ def process_control(program): parts = get_parts(program) names = dict(pair for pair in zip(parts, generate_index())) correct_control(program, names) def get_parts(program): parts = [] for ins in program: if isinstance(ins, tuple): ins, arg = ins if ins == INS.PART: if arg in parts: raise NameError('Part definition was found twice: ' + arg) parts.append(arg) return parts def generate_index(): index = 1 while True: yield index index *= -1 if index > 0: index += 1 def correct_control(program, names): for index, ins in enumerate(program): if isinstance(ins, tuple): ins, arg = ins if ins in HAS_LABEL: if arg not in names: raise NameError('Part definition was never found: ' + arg) program[index] = (ins, names[arg]) ################################################################################ def parse_part(program, line, text): if not valid_label(text): syntax_error(line) program.append((INS.PART, text)) def valid_label(text): if not between_quotes(text): return False label = text[1:-1] if not valid_name(label): return False return True def between_quotes(text): if len(text) < 3: return False if text.count('"') != 2: return False if text[0] != '"' or text[-1] != '"': return False return True def valid_name(label): valid_characters = string.ascii_letters + string.digits + '_' valid_set = frozenset(valid_characters) label_set = frozenset(label) if len(label_set - valid_set) != 0: return False return True ################################################################################ from Interpreter import HAS_LABEL, Program NO_ARGS = Program.NO_ARGS HAS_ARG = Program.HAS_ARG TWO_WAY = tuple(set(NO_ARGS) & set(HAS_ARG)) ################################################################################ def parse_code(program, line, text): for ins, word in enumerate(MNEMONIC): if text.startswith(word): check_code(program, line, text[len(word):], ins) break else: syntax_error(line) def check_code(program, line, text, ins): if ins in TWO_WAY: if text: number = parse_number(line, text) program.append((ins, number)) else: program.append(ins) elif ins in HAS_LABEL: text = parse_label(line, text) program.append((ins, text)) elif ins in HAS_ARG: number = parse_number(line, text) program.append((ins, number)) elif ins in NO_ARGS: if text: syntax_error(line) program.append(ins) else: syntax_error(line) def parse_label(line, text): if not text or text[0] != ' ': syntax_error(line) text = text[1:] if not valid_label(text): syntax_error(line) return text ################################################################################ def parse_number(line, text): if not valid_number(text): syntax_error(line) return int(text) def valid_number(text): if len(text) < 2: return False if text[0] != ' ': return False text = text[1:] if '+' in text and '-' in text: return False if '+' in text: if text.count('+') != 1: return False if text[0] != '+': return False text = text[1:] if not text: return False if '-' in text: if text.count('-') != 1: return False if text[0] != '-': return False text = text[1:] if not text: return False valid_set = frozenset(string.digits) value_set = frozenset(text) if len(value_set - valid_set) != 0: return False return True ################################################################################ ################################################################################ from Interpreter import partition_number VMC_2_TRI = { (INS.PUSH, True): (0, 0), (INS.COPY, False): (0, 2, 0), (INS.COPY, True): (0, 1, 0), (INS.SWAP, False): (0, 2, 1), (INS.AWAY, False): (0, 2, 2), (INS.AWAY, True): (0, 1, 2), (INS.ADD, False): (1, 0, 0, 0), (INS.SUB, False): (1, 0, 0, 1), (INS.MUL, False): (1, 0, 0, 2), (INS.DIV, False): (1, 0, 1, 0), (INS.MOD, False): (1, 0, 1, 1), (INS.SET, False): (1, 1, 0), (INS.GET, False): (1, 1, 1), (INS.PART, True): (2, 0, 0), (INS.CALL, True): (2, 0, 1), (INS.GOTO, True): (2, 0, 2), (INS.ZERO, True): (2, 1, 0), (INS.LESS, True): (2, 1, 1), (INS.BACK, False): (2, 1, 2), (INS.EXIT, False): (2, 2, 2), (INS.OCHR, False): (1, 2, 0, 0), (INS.OINT, False): (1, 2, 0, 1), (INS.ICHR, False): (1, 2, 1, 0), (INS.IINT, False): (1, 2, 1, 1) } ################################################################################ def to_trinary(program): trinary_code = [] for ins in program: if isinstance(ins, tuple): ins, arg = ins trinary_code.extend(VMC_2_TRI[(ins, True)]) trinary_code.extend(from_number(arg)) else: trinary_code.extend(VMC_2_TRI[(ins, False)]) return tuple(trinary_code) def from_number(arg): code = [int(arg < 0)] if arg: for bit in reversed(list(partition_number(abs(arg), 2))): code.append(bit) return code + [2] return code + [0, 2] to_ws = lambda trinary: ''.join(' \t\n'[index] for index in trinary) def compile_wsa(source): program = parse(source) trinary = to_trinary(program) ws_code = to_ws(trinary) return ws_code ################################################################################ ################################################################################ import os import sys import time import traceback def main(): name, source, command_line, error = get_source() if not error: start = time.clock() try: ws_code = compile_wsa(source) except: print('ERROR: File could not be compiled.\n') traceback.print_exc() error = True else: path = os.path.join('Programs', name + '.ws') try: open(path, 'w').write(ws_code) except IOError as err: print(err) error = True else: div, mod = divmod((time.clock() - start) * 1000, 1) args = int(div), '{:.3}'.format(mod)[1:] print('DONE: Comipled in {}{} ms'.format(*args)) handle_close(error, command_line) def get_source(): if len(sys.argv) > 1: command_line = True name = sys.argv[1] else: command_line = False try: name = input('Source File: ') except: return None, None, False, True print() path = os.path.join('Assembly', name + '.wsa') try: return name, open(path).read(), command_line, False except IOError as err: print(err) return None, None, command_line, True def handle_close(error, command_line): if error: usage = 'Usage: {} <assembly>'.format(os.path.basename(sys.argv[0])) print('\n{}\n{}'.format('-' * len(usage), usage)) if not command_line: time.sleep(10) ################################################################################ if __name__ == '__main__': main() Whitespace Helpers #! /usr/bin/env python """Helpers.py Includes a function to encode Python strings into my WSA format. Has a "PRINT_LINE" function that can be copied to a WSA program. Contains a "PRINT" function and documentation as an explanation.""" ################################################################################ __author__ = 'Stephen "Zero" Chappell <[email protected]>' __date__ = '14 March 2010' __version__ = '$Revision: 1 $' ################################################################################ def encode_string(string, addr): print(' push', addr) print(' push', len(string)) print(' set') addr += 1 for offset, character in enumerate(string): print(' push', addr + offset) print(' push', ord(character)) print(' set') ################################################################################ # Prints a string with newline. # push addr # call "PRINT_LINE" """ part "PRINT_LINE" call "PRINT" push 10 ochr back """ ################################################################################ # def print(array): # if len(array) <= 0: # return # offset = 1 # while len(array) - offset >= 0: # ptr = array.ptr + offset # putch(array[ptr]) # offset += 1 """ part "PRINT" # Line 1-2 copy get less "__PRINT_RET_1" copy get zero "__PRINT_RET_1" # Line 3 push 1 # Line 4 part "__PRINT_LOOP" copy copy 2 get swap sub less "__PRINT_RET_2" # Line 5 copy 1 copy 1 add # Line 6 get ochr # Line 7 push 1 add goto "__PRINT_LOOP" part "__PRINT_RET_2" away part "__PRINT_RET_1" away back """ Whitespace Interpreter #! /usr/bin/env python """Interpreter.py Runs programs in "Programs" and creates *.WSO files when needed. Can be executed directly by double-click or on the command line. If run on command line, add "ASM" flag to dump program assembly.""" ################################################################################ __author__ = 'Stephen "Zero" Chappell <[email protected]>' __date__ = '14 March 2010' __version__ = '$Revision: 4 $' ################################################################################ def test_file(path): disassemble(parse(trinary(load(path))), True) ################################################################################ load = lambda ws: ''.join(c for r in open(ws) for c in r if c in ' \t\n') trinary = lambda ws: tuple(' \t\n'.index(c) for c in ws) ################################################################################ def enum(names): names = names.replace(',', ' ').split() space = dict((reversed(pair) for pair in enumerate(names)), __slots__=()) return type('enum', (object,), space)() INS = enum('''\ PUSH, COPY, SWAP, AWAY, \ ADD, SUB, MUL, DIV, MOD, \ SET, GET, \ PART, CALL, GOTO, ZERO, LESS, BACK, EXIT, \ OCHR, OINT, ICHR, IINT''') ################################################################################ def parse(code): ins = iter(code).__next__ program = [] while True: try: imp = ins() except StopIteration: return tuple(program) if imp == 0: # [Space] parse_stack(ins, program) elif imp == 1: # [Tab] imp = ins() if imp == 0: # [Tab][Space] parse_math(ins, program) elif imp == 1: # [Tab][Tab] parse_heap(ins, program) else: # [Tab][Line] parse_io(ins, program) else: # [Line] parse_flow(ins, program) def parse_number(ins): sign = ins() if sign == 2: raise StopIteration() buffer = '' code = ins() if code == 2: raise StopIteration() while code != 2: buffer += str(code) code = ins() if sign == 1: return int(buffer, 2) * -1 return int(buffer, 2) ################################################################################ def parse_stack(ins, program): code = ins() if code == 0: # [Space] number = parse_number(ins) program.append((INS.PUSH, number)) elif code == 1: # [Tab] code = ins() number = parse_number(ins) if code == 0: # [Tab][Space] program.append((INS.COPY, number)) elif code == 1: # [Tab][Tab] raise StopIteration() else: # [Tab][Line] program.append((INS.AWAY, number)) else: # [Line] code = ins() if code == 0: # [Line][Space] program.append(INS.COPY) elif code == 1: # [Line][Tab] program.append(INS.SWAP) else: # [Line][Line] program.append(INS.AWAY) def parse_math(ins, program): code = ins() if code == 0: # [Space] code = ins() if code == 0: # [Space][Space] program.append(INS.ADD) elif code == 1: # [Space][Tab] program.append(INS.SUB) else: # [Space][Line] program.append(INS.MUL) elif code == 1: # [Tab] code = ins() if code == 0: # [Tab][Space] program.append(INS.DIV) elif code == 1: # [Tab][Tab] program.append(INS.MOD) else: # [Tab][Line] raise StopIteration() else: # [Line] raise StopIteration() def parse_heap(ins, program): code = ins() if code == 0: # [Space] program.append(INS.SET) elif code == 1: # [Tab] program.append(INS.GET) else: # [Line] raise StopIteration() def parse_io(ins, program): code = ins() if code == 0: # [Space] code = ins() if code == 0: # [Space][Space] program.append(INS.OCHR) elif code == 1: # [Space][Tab] program.append(INS.OINT) else: # [Space][Line] raise StopIteration() elif code == 1: # [Tab] code = ins() if code == 0: # [Tab][Space] program.append(INS.ICHR) elif code == 1: # [Tab][Tab] program.append(INS.IINT) else: # [Tab][Line] raise StopIteration() else: # [Line] raise StopIteration() def parse_flow(ins, program): code = ins() if code == 0: # [Space] code = ins() label = parse_number(ins) if code == 0: # [Space][Space] program.append((INS.PART, label)) elif code == 1: # [Space][Tab] program.append((INS.CALL, label)) else: # [Space][Line] program.append((INS.GOTO, label)) elif code == 1: # [Tab] code = ins() if code == 0: # [Tab][Space] label = parse_number(ins) program.append((INS.ZERO, label)) elif code == 1: # [Tab][Tab] label = parse_number(ins) program.append((INS.LESS, label)) else: # [Tab][Line] program.append(INS.BACK) else: # [Line] code = ins() if code == 2: # [Line][Line] program.append(INS.EXIT) else: # [Line][Space] or [Line][Tab] raise StopIteration() ################################################################################ MNEMONIC = '\ push copy swap away add sub mul div mod set get part \ call goto zero less back exit ochr oint ichr iint'.split() HAS_ARG = [getattr(INS, name) for name in 'PUSH COPY AWAY PART CALL GOTO ZERO LESS'.split()] HAS_LABEL = [getattr(INS, name) for name in 'PART CALL GOTO ZERO LESS'.split()] def disassemble(program, names=False): if names: names = create_names(program) for ins in program: if isinstance(ins, tuple): ins, arg = ins assert ins in HAS_ARG has_arg = True else: assert INS.PUSH <= ins <= INS.IINT has_arg = False if ins == INS.PART: if names: print(MNEMONIC[ins], '"' + names[arg] + '"') else: print(MNEMONIC[ins], arg) elif has_arg and ins in HAS_ARG: if ins in HAS_LABEL and names: assert arg in names print(' ' + MNEMONIC[ins], '"' + names[arg] + '"') else: print(' ' + MNEMONIC[ins], arg) else: print(' ' + MNEMONIC[ins]) ################################################################################ def create_names(program): names = {} number = 1 for ins in program: if isinstance(ins, tuple) and ins[0] == INS.PART: label = ins[1] assert label not in names names[label] = number_to_name(number) number += 1 return names def number_to_name(number): name = '' for offset in reversed(list(partition_number(number, 27))): if offset: name += chr(ord('A') + offset - 1) else: name += '_' return name def partition_number(number, base): div, mod = divmod(number, base) yield mod while div: div, mod = divmod(div, base) yield mod ################################################################################ CODE = (' \t\n', ' \n ', ' \t \t\n', ' \n\t', ' \n\n', ' \t\n \t\n', '\t ', '\t \t', '\t \n', '\t \t ', '\t \t\t', '\t\t ', '\t\t\t', '\n \t\n', '\n \t \t\n', '\n \n \t\n', '\n\t \t\n', '\n\t\t \t\n', '\n\t\n', '\n\n\n', '\t\n ', '\t\n \t', '\t\n\t ', '\t\n\t\t') EXAMPLE = ''.join(CODE) ################################################################################ NOTES = '''\ STACK ===== push number copy copy number swap away away number MATH ==== add sub mul div mod HEAP ==== set get FLOW ==== part label call label goto label zero label less label back exit I/O === ochr oint ichr iint''' ################################################################################ ################################################################################ class Stack: def __init__(self): self.__data = [] # Stack Operators def push(self, number): self.__data.append(number) def copy(self, number=None): if number is None: self.__data.append(self.__data[-1]) else: size = len(self.__data) index = size - number - 1 assert 0 <= index < size self.__data.append(self.__data[index]) def swap(self): self.__data[-2], self.__data[-1] = self.__data[-1], self.__data[-2] def away(self, number=None): if number is None: self.__data.pop() else: size = len(self.__data) index = size - number - 1 assert 0 <= index < size del self.__data[index:-1] # Math Operators def add(self): suffix = self.__data.pop() prefix = self.__data.pop() self.__data.append(prefix + suffix) def sub(self): suffix = self.__data.pop() prefix = self.__data.pop() self.__data.append(prefix - suffix) def mul(self): suffix = self.__data.pop() prefix = self.__data.pop() self.__data.append(prefix * suffix) def div(self): suffix = self.__data.pop() prefix = self.__data.pop() self.__data.append(prefix // suffix) def mod(self): suffix = self.__data.pop() prefix = self.__data.pop() self.__data.append(prefix % suffix) # Program Operator def pop(self): return self.__data.pop() ################################################################################ class Heap: def __init__(self): self.__data = {} def set_(self, addr, item): if item: self.__data[addr] = item elif addr in self.__data: del self.__data[addr] def get_(self, addr): return self.__data.get(addr, 0) ################################################################################ import os import zlib import msvcrt import pickle import string class CleanExit(Exception): pass NOP = lambda arg: None DEBUG_WHITESPACE = False ################################################################################ class Program: NO_ARGS = INS.COPY, INS.SWAP, INS.AWAY, INS.ADD, \ INS.SUB, INS.MUL, INS.DIV, INS.MOD, \ INS.SET, INS.GET, INS.BACK, INS.EXIT, \ INS.OCHR, INS.OINT, INS.ICHR, INS.IINT HAS_ARG = INS.PUSH, INS.COPY, INS.AWAY, INS.PART, \ INS.CALL, INS.GOTO, INS.ZERO, INS.LESS def __init__(self, code): self.__data = code self.__validate() self.__build_jump() self.__check_jump() self.__setup_exec() def __setup_exec(self): self.__iptr = 0 self.__stck = stack = Stack() self.__heap = Heap() self.__cast = [] self.__meth = (stack.push, stack.copy, stack.swap, stack.away, stack.add, stack.sub, stack.mul, stack.div, stack.mod, self.__set, self.__get, NOP, self.__call, self.__goto, self.__zero, self.__less, self.__back, self.__exit, self.__ochr, self.__oint, self.__ichr, self.__iint) def step(self): ins = self.__data[self.__iptr] self.__iptr += 1 if isinstance(ins, tuple): self.__meth[ins[0]](ins[1]) else: self.__meth[ins]() def run(self): while True: ins = self.__data[self.__iptr] self.__iptr += 1 if isinstance(ins, tuple): self.__meth[ins[0]](ins[1]) else: self.__meth[ins]() def __oint(self): for digit in str(self.__stck.pop()): msvcrt.putwch(digit) def __ichr(self): addr = self.__stck.pop() # Input Routine while msvcrt.kbhit(): msvcrt.getwch() while True: char = msvcrt.getwch() if char in '\x00\xE0': msvcrt.getwch() elif char in string.printable: char = char.replace('\r', '\n') msvcrt.putwch(char) break item = ord(char) # Storing Number self.__heap.set_(addr, item) def __iint(self): addr = self.__stck.pop() # Input Routine while msvcrt.kbhit(): msvcrt.getwch() buff = '' char = msvcrt.getwch() while char != '\r' or not buff: if char in '\x00\xE0': msvcrt.getwch() elif char in '+-' and not buff: msvcrt.putwch(char) buff += char elif '0' <= char <= '9': msvcrt.putwch(char) buff += char elif char == '\b': if buff: buff = buff[:-1] msvcrt.putwch(char) msvcrt.putwch(' ') msvcrt.putwch(char) char = msvcrt.getwch() msvcrt.putwch(char) msvcrt.putwch('\n') item = int(buff) # Storing Number self.__heap.set_(addr, item) def __goto(self, label): self.__iptr = self.__jump[label] def __zero(self, label): if self.__stck.pop() == 0: self.__iptr = self.__jump[label] def __less(self, label): if self.__stck.pop() < 0: self.__iptr = self.__jump[label] def __exit(self): self.__setup_exec() raise CleanExit() def __set(self): item = self.__stck.pop() addr = self.__stck.po

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  • FluentPath: a fluent wrapper around System.IO

    .NET is now more than eight years old, and some of its APIs got old with more grace than others. System.IO in particular has always been a little awkward. Its mostly static method calls (Path.*, Directory.*, etc.) and some stateful classes (DirectoryInfo, FileInfo). In these APIs, paths are plain strings. Since .NET v1, lots of good things happened to C#: lambda expressions, extension methods, optional parameters to name just a few. Outside of .NET, other interesting things happened as well. For...Did you know that DotNetSlackers also publishes .net articles written by top known .net Authors? We already have over 80 articles in several categories including Silverlight. Take a look: here.

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  • Project Euler 8: (Iron)Python

    - by Ben Griswold
    In my attempt to learn (Iron)Python out in the open, here’s my solution for Project Euler Problem 8.  As always, any feedback is welcome. # Euler 8 # http://projecteuler.net/index.php?section=problems&id=8 # Find the greatest product of five consecutive digits # in the following 1000-digit number import time start = time.time() number = '\ 73167176531330624919225119674426574742355349194934\ 96983520312774506326239578318016984801869478851843\ 85861560789112949495459501737958331952853208805511\ 12540698747158523863050715693290963295227443043557\ 66896648950445244523161731856403098711121722383113\ 62229893423380308135336276614282806444486645238749\ 30358907296290491560440772390713810515859307960866\ 70172427121883998797908792274921901699720888093776\ 65727333001053367881220235421809751254540594752243\ 52584907711670556013604839586446706324415722155397\ 53697817977846174064955149290862569321978468622482\ 83972241375657056057490261407972968652414535100474\ 82166370484403199890008895243450658541227588666881\ 16427171479924442928230863465674813919123162824586\ 17866458359124566529476545682848912883142607690042\ 24219022671055626321111109370544217506941658960408\ 07198403850962455444362981230987879927244284909188\ 84580156166097919133875499200524063689912560717606\ 05886116467109405077541002256983155200055935729725\ 71636269561882670428252483600823257530420752963450' max = 0 for i in xrange(0, len(number) - 5): nums = [int(x) for x in number[i:i+5]] val = reduce(lambda agg, x: agg*x, nums) if val > max: max = val print max print "Elapsed Time:", (time.time() - start) * 1000, "millisecs" a=raw_input('Press return to continue')

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  • Links to C++ documentation

    - by Daniel Moth
    After a recent talk I gave on C++ AMP, one attendee was complaining that they were not familiar with lambdas and another found templates hard to parse. In case you are in the same boat, I thought I'd gather some essential reading material for you (also gives me one link to use in the future for referring people to ;-) Lambdas are available (in some shape or form) in all modern languages, so do yourself a favor and learn about them: Lambda Expressions in C++ (and also syntax and examples) Watch Herb Sutter's full length session on lambdas at PDC 2010 Templates, have been around in modern languages for even longer than lambdas (e.g. Generics in .NET), so again go dive in: Templates topic with full table of contents linking to subtopics In fact, why don't you refresh your knowledge and read the entire msdn C++ Language Reference – that's what I am doing! If you are looking to keep up to date with what is happening in the C++ world, stay tuned on the Visual C++ team (aka WinC++ team) blog and ask questions in the C++ forums. Comments about this post welcome at the original blog.

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  • Chuck Esterbrook: Geek of the Week

    The Cobra Programming Language is an exciting new general-purpose Open-source language for .NET or Mono, which features unit tests, contracts, informative asserts, generics, Compile-time nil/null tracking, lambda expressions, closures, list comprehensions and generators. Even if it had been developed by a team, it would have been a remarkable achievement. The surprise is that it is the work of one programmer with help from a group of users. We sent Richard to find out more about that one progra...Did you know that DotNetSlackers also publishes .net articles written by top known .net Authors? We already have over 80 articles in several categories including Silverlight. Take a look: here.

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