Search Results

Search found 35200 results on 1408 pages for 't string'.

facebook twitter digg google delicious technorati stumbleupon myspace wordpress linkedin gmail igoogle windows live tumblr viadeo yahoo buzz yahoo mail yahoo bookmarks favorites email print

Page 881/1408 | < Previous Page | 877 878 879 880 881 882 883 884 885 886 887 888  | Next Page >

  • Dealing with external processes

    - by Jesse Aldridge
    I've been working on a gui app that needs to manage external processes. Working with external processes leads to a lot of issues that can make a programmer's life difficult. I feel like maintenence on this app is taking an unacceptably long time. I've been trying to list the things that make working with external processes difficult so that I can come up with ways of mitigating the pain. This kind of turned into a rant which I thought I'd post here in order to get some feedback and to provide some guidance to anybody thinking about sailing into these very murky waters. Here's what I've got so far: Output from the child can get mixed up with output from the parent. This can make both outputs misleading and hard to read. It can be hard to tell what came from where. It becomes harder to figure out what's going on when things are asynchronous. Here's a contrived example: import textwrap, os, time from subprocess import Popen test_path = 'test_file.py' with open(test_path, 'w') as file: file.write(textwrap.dedent(''' import time for i in range(3): print 'Hello %i' % i time.sleep(1)''')) proc = Popen('python -B "%s"' % test_path) for i in range(3): print 'Hello %i' % i time.sleep(1) os.remove(test_path) I guess I could have the child process write its output to a file. But it can be annoying to have to open up a file every time I want to see the result of a print statement. If I have code for the child process I could add a label, something like print 'child: Hello %i', but it can be annoying to do that for every print. And it adds some noise to the output. And of course I can't do it if I don't have access to the code. I could manually manage the process output. But then you open up a huge can of worms with threads and polling and stuff like that. A simple solution is to treat processes like synchronous functions, that is, no further code executes until the process completes. In other words, make the process block. But that doesn't work if you're building a gui app. Which brings me to the next problem... Blocking processes cause the gui to become unresponsive. import textwrap, sys, os from subprocess import Popen from PyQt4.QtGui import * from PyQt4.QtCore import * test_path = 'test_file.py' with open(test_path, 'w') as file: file.write(textwrap.dedent(''' import time for i in range(3): print 'Hello %i' % i time.sleep(1)''')) app = QApplication(sys.argv) button = QPushButton('Launch process') def launch_proc(): # Can't move the window until process completes proc = Popen('python -B "%s"' % test_path) proc.communicate() button.connect(button, SIGNAL('clicked()'), launch_proc) button.show() app.exec_() os.remove(test_path) Qt provides a process wrapper of its own called QProcess which can help with this. You can connect functions to signals to capture output relatively easily. This is what I'm currently using. But I'm finding that all these signals behave suspiciously like goto statements and can lead to spaghetti code. I think I want to get sort-of blocking behavior by having the 'finished' signal from QProcess call a function containing all the code that comes after the process call. I think that should work but I'm still a bit fuzzy on the details... Stack traces get interrupted when you go from the child process back to the parent process. If a normal function screws up, you get a nice complete stack trace with filenames and line numbers. If a subprocess screws up, you'll be lucky if you get any output at all. You end up having to do a lot more detective work everytime something goes wrong. Speaking of which, output has a way of disappearing when dealing external processes. Like if you run something via the windows 'cmd' command, the console will pop up, execute the code, and then disappear before you have a chance to see the output. You have to pass the /k flag to make it stick around. Similar issues seem to crop up all the time. I suppose both problems 3 and 4 have the same root cause: no exception handling. Exception handling is meant to be used with functions, it doesn't work with processes. Maybe there's some way to get something like exception handling for processes? I guess that's what stderr is for? But dealing with two different streams can be annoying in itself. Maybe I should look into this more... Processes can hang and stick around in the background without you realizing it. So you end up yelling at your computer cuz it's going so slow until you finally bring up your task manager and see 30 instances of the same process hanging out in the background. Also, hanging background processes can interefere with other instances of the process in various fun ways, such as causing permissions errors by holding a handle to a file or someting like that. It seems like an easy solution to this would be to have the parent process kill the child process on exit if the child process didn't close itself. But if the parent process crashes, cleanup code might not get called and the child can be left hanging. Also, if the parent waits for the child to complete, and the child is in an infinite loop or something, you can end up with two hanging processes. This problem can tie in to problem 2 for extra fun, causing your gui to stop responding entirely and force you to kill everything with the task manager. F***ing quotes Parameters often need to be passed to processes. This is a headache in itself. Especially if you're dealing with file paths. Say... 'C:/My Documents/whatever/'. If you don't have quotes, the string will often be split at the space and interpreted as two arguments. If you need nested quotes you can use ' and ". But if you need to use more than two layers of quotes, you have to do some nasty escaping, for example: "cmd /k 'python \'path 1\' \'path 2\''". A good solution to this problem is passing parameters as a list rather than as a single string. Subprocess allows you to do this. Can't easily return data from a subprocess. You can use stdout of course. But what if you want to throw a print in there for debugging purposes? That's gonna screw up the parent if it's expecting output formatted a certain way. In functions you can print one string and return another and everything works just fine. Obscure command-line flags and a crappy terminal based help system. These are problems I often run into when using os level apps. Like the /k flag I mentioned, for holding a cmd window open, who's idea was that? Unix apps don't tend to be much friendlier in this regard. Hopefully you can use google or StackOverflow to find the answer you need. But if not, you've got a lot of boring reading and frusterating trial and error to do. External factors. This one's kind of fuzzy. But when you leave the relatively sheltered harbor of your own scripts to deal with external processes you find yourself having to deal with the "outside world" to a much greater extent. And that's a scary place. All sorts of things can go wrong. Just to give a random example: the cwd in which a process is run can modify it's behavior. There are probably other issues, but those are the ones I've written down so far. Any other snags you'd like to add? Any suggestions for dealing with these problems?

    Read the article

  • List MySQL enum in Java

    - by Pieter
    Is there a way to get all possible values from a MySQL enum column? The MySQL documentation says the MySQL enum type is returned as a Java String, so I basically would like a way to get all possible strings I can pass when querying a table with such an enum. I couldn't immediately find anything when I was looking through the metadata returned for such a column, but since enum isn't standard SQL, I'm not sure it's even possible... any suggestions?

    Read the article

  • "This Friday" in bash script

    - by Ben
    Hi, Is there a way to calculate a time stamp for the next coming up of a week day? So for instance, with friday, i'd like to be able to run some code that calculates that from today Wednesday 19/05/10, the next friday will be 21/05/10 and get a time stamp from it. I know the date command can parse a given string date according to a format, but I can't figure out how to calculate "next friday from today" Any idea? Cheers Ben

    Read the article

  • Define polynomial function

    - by user1822707
    How can I define a function - say, def polyToString(poly) - to return a string containing the polynomial poly in standard form? For example: the polynomial represented by [-1, 2, -3, 4, -5] would be returned as: "-5x**4 + 4x**3 -3x**2 + 2x**1 - 1x**0" def polyToString(poly): standard_form='' n=len(poly) - 1 while n >=0: if poly[n]>=0: if n==len(poly)-1: standard_form= standard_form + ' '+ str(poly[n]) + 'x**%d'%n else: standard_form= standard_form + ' + '+str(poly[n]) + 'x**%d'%n else: standard_form= standard_form + ' - ' + str(abs(poly[n])) + 'x**' + str(n) n=n-1 return standard_form

    Read the article

  • Formatting in a UITextView

    - by richard Stephenson
    hi all , im having problems with formatting for a UITextView. my app pulls in XML, saves some of it to a string , and then displays the text in a UITextView. it understands if you put a return in there, and it starts a new line. but i want to put paragraphs in there, any idea how i can pass that information without doing multiple UITextViews Thanks :)

    Read the article

  • How do I check mysql user have privileges like root user

    - by Devara Gudda
    I use mysql c++ wrapper in client side to connect to mysql server. When user establishes connection to mysql server I want to know whether the user have privileges like root (i.e. GRANT ALL PRIVILEGES ON . TO 'username'@'%' WITH GRANT OPTION).The 'SHOW GRANTS FOR CURRENT_USER' query gives grants for current user, but i need to parse the string and compare to know whether the current user have privileges like root. I am looking for an alternative options. Regards, Devara Gudda

    Read the article

  • Rails 3 Nested Forms with datamapper

    - by jens freudenau
    i have two models: class MeetingPoint include DataMapper::Resource belongs_to :profile property :id, Serial property :lat, String end and class Profile include DataMapper::Resource has n, :meeting_points property :id, Serial property :distance, Text property :created_at, DateTime property :updated_at, DateTime end Now I create a form to edit the profile and the meeting_poing: = form_for @profile do |f| = f.text_field :distance = f.fields_for :meeting_points do |ff| = ff.text_field :lat = f.submit But when I want to save the values I get always the error: "undefined method `readonly?' for ["lat", "14.000"]:Array"

    Read the article

  • Set the title of a UIButton with a single method invocation?

    - by Greg Maletic
    I'd like to set the title of a UIButton via code. I find myself having to call -[UIButton setTitle:forState:] for UIControlStateNormal, UIControlStateHighlighted, UIControlStateDisabled, UIControlStateSelected. And that doesn't even take into account all of the combinations of these states together. Needless to say, this is tiresome. Is there a single call I can make that will set one string as the title for all of the states? (Since, I assume that in 95% of the cases, that's the desired behavior?)

    Read the article

  • Regular expressions and matching question marks in URLs

    - by James P.
    I'm having trouble finding a regular expression that matches the following String. Korben;http://feeds.feedburner.com/KorbensBlog-UpgradeYourMind?format=xml;1 One problem is escaping the question mark. Java's pattern matcher doesn't seem to accept \? as a valid escape sequence but it also fails to work with the tester at myregexp.com. Here's what I have so far: ([a-zA-Z0-9])+;http://([a-zA-Z0-9./-]+);[0-9]+ Any suggestions?

    Read the article

  • Is there a way to add or remove a line of an LINQ to DB Query based on if the value being checked is

    - by RandomBen
    If I have a query like this: String Category = HttpContext.Current.Request.QueryString["Product"].ToString(); IQueryable<ItemFile> pressReleases = from file in connection.ItemFile where file.Type_ID == 8 && file.Category == Category select file; Is there a way to make this LINQ Query so that I do no use the line file.Category == Category if Category is null or empty?

    Read the article

  • Saving commands for later re-use in MySQL?

    - by Zombies
    What would be the equivalant in MySQL for: Saving a command for later reuse. eg: alias command1='select count(*) from sometable;' Where then I simply type command 1 to get the count for SomeTable. Saving just a string, or rather part of a command. eg: select * from sometable where $complex_where_logic$ order by attr1 desc; WHere $complex_where_logic$ is something I wish to save and not have to keep writing out

    Read the article

  • VBA regex pattern

    - by KeyMs92
    This is probably a simple problem, but unfortunately I wasn't able to get the results I wanted... Say, I have the following line: "Wouldn't It Be Nice" (B. Wilson/Asher/Love) I would have to look for this pattern: " (<any string>) In order to retrieve: B. Wilson/Asher/Love I tried something like "" (([^))]*)) but it doesn't seem to work. Also, I'd like to use Match.Submatches(0) so that might complicate things a bit because it relies on brackets...

    Read the article

  • BeanDefinition class removed in Spring 4?

    - by mushtaq
    I am trying out the new Spring 4 release, and I found out that the BeanDefinition interface has been removed, if so what is the replacement class we should use in a scenario where we define a scope for a bean ? Prior to Spring release of 4 you could do this. @Bean @Scope(BeanDefinition.SCOPE_PROTOTYPE) class MyBean{ ... } EDIT As of Spring 4, can't you specify the spring bean scope in the @Scope Annotation, the only option given is to add a string and then the ProxyMode ?

    Read the article

  • How to view ASMX SOAP using Fiddler2?

    - by outer join
    Does anyone know if Fiddler can display the raw SOAP messages for ASMX web services? I'm testing a simple web service using both Fiddler2 and Storm and the results vary (Fiddler shows plain xml while Storm shows the SOAP messages). See sample request/responses below: Fiddler2 Request: POST /webservice1.asmx/Test HTTP/1.1 Accept: */* Referer: http://localhost.:4164/webservice1.asmx?op=Test Accept-Language: en-us User-Agent: Mozilla/4.0 (compatible; MSIE 8.0; Windows NT 5.1; Trident/4.0; .NET CLR 1.1.4322; .NET CLR 2.0.50727; .NET CLR 3.0.04506.30; .NET CLR 3.0.04506.648; .NET CLR 3.5.21022; .NET CLR 3.0.4506.2152; .NET CLR 3.5.30729; InfoPath.2; MS-RTC LM 8) Content-Type: application/x-www-form-urlencoded Accept-Encoding: gzip, deflate Host: localhost.:4164 Content-Length: 0 Connection: Keep-Alive Pragma: no-cache Fiddler2 Response: HTTP/1.1 200 OK Server: ASP.NET Development Server/9.0.0.0 Date: Thu, 21 Jan 2010 14:21:50 GMT X-AspNet-Version: 2.0.50727 Cache-Control: private, max-age=0 Content-Type: text/xml; charset=utf-8 Content-Length: 96 Connection: Close <?xml version="1.0" encoding="utf-8"?> <string xmlns="http://tempuri.org/">Hello World</string> Storm Request (body only): <?xml version="1.0" encoding="utf-8"?> <soap:Envelope xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:soap="http://schemas.xmlsoap.org/soap/envelope/"> <soap:Body> <Test xmlns="http://tempuri.org/" /> </soap:Body> </soap:Envelope> Storm Response: Status Code: 200 Content Length : 339 Content Type: text/xml; charset=utf-8 Server: ASP.NET Development Server/9.0.0.0 Status Description: OK <?xml version="1.0" encoding="utf-8"?> <soap:Envelope xmlns:soap="http://schemas.xmlsoap.org/soap/envelope/" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema"> <soap:Body> <TestResponse xmlns="http://tempuri.org/"> <TestResult>Hello World</TestResult> </TestResponse> </soap:Body> </soap:Envelope> Thanks for any help.

    Read the article

  • Regular Expression Longes Possible Matching

    - by syker
    So I have an input string which is a directory addres: Example: ProgramFiles/Micro/Telephone And I want to match it against a list of words very strictly: Example: Tel|Tele|Telephone I want to match against Telephone and not Tel. Right now my reg looks like this: my( $output ) = ( $input =~ m/($list)/o ); The regex above will match against Tel. What can I do to fix it?

    Read the article

  • Questions on SQL Server 2008 Full-Text Search

    - by Eddie
    I have some questions about SQL 2K8 integrated full-text search. Say I have the following tables: Car with columns: id (int - pk), makeid (fk), description (nvarchar), year (int), features (int - bitwise value - 32 features only) CarMake with columns: id (int - pk), mfgname (nvarchar) CarFeatures with columns: id (int - 1, 2, 4, 8, etc.), featurename (nvarchar) If someone searches "red honda civic 2002 4 doors", how would I parse the input string so that I could also search in the "CarMake" and "CarFeatures" tables?

    Read the article

  • document.write buggy?

    - by proyb2
    Something wrong with the code? I could print Hello on HTML but when I add to getPlayerVersion, the whole string doesn't print. What could be problem be? Leaving me feeling frustrated. <script type="text/javascript"> document.write("Hello"+deconcept.SWFObjectUtil.getPlayerVersion().major); </script>

    Read the article

  • Java strings and substrings

    - by omaxgreen
    hey folks, Can someone help me with this Java problem? I want to write a method that takes two strings as arguments and returns true if each character (including space and punctuation) that appears in one string also appears in the other. Thanks

    Read the article

  • Can I parse uri from resource?

    - by DYH1919
    // startActivity(new Intent(Intent.ACTION_VIEW, Uri.parse(getString(R.string.donate_url)))); startActivity(new Intent(Intent.ACTION_VIEW, Uri.parse("http://www.google.com"))); when I use the first,app will crash in emulator but the second run well, how can I fix the first? thanks for help

    Read the article

  • "Can't mass-assign protected attributes" with nested protected models

    - by JohnnyFive
    I'm having a hell of a time trying to get this nested model working. I've tried all manner of pluralization/singular, removing the attr_accessible altogether, and who knows what else. restaurant.rb: # == RESTAURANT MODEL # # Table name: restaurants # # id :integer not null, primary key # name :string(255) # created_at :datetime not null # updated_at :datetime not null # class Restaurant < ActiveRecord::Base attr_accessible :name, :job_attributes has_many :jobs has_many :users, :through => :jobs has_many :positions accepts_nested_attributes_for :jobs, :allow_destroy => true validates :name, presence: true end job.rb: # == JOB MODEL # # Table name: jobs # # id :integer not null, primary key # restaurant_id :integer # shortname :string(255) # user_id :integer # created_at :datetime not null # updated_at :datetime not null # class Job < ActiveRecord::Base attr_accessible :restaurant_id, :shortname, :user_id belongs_to :user belongs_to :restaurant has_many :shifts validates :name, presence: false end restaurants_controller.rb: class RestaurantsController < ApplicationController before_filter :logged_in, only: [:new_restaurant] def new @restaurant = Restaurant.new @user = current_user end def create @restaurant = Restaurant.new(params[:restaurant]) if @restaurant.save flash[:success] = "Restaurant created." redirect_to welcome_path end end end new.html.erb: <% provide(:title, 'Restaurant') %> <%= form_for @restaurant do |f| %> <%= render 'shared/error_messages' %> <%= f.label "Restaurant Name" %> <%= f.text_field :name %> <%= f.fields_for :job do |child_f| %> <%= child_f.label "Nickname" %> <%= child_f.text_field :shortname %> <% end %> <%= f.submit "Done", class: "btn btn-large btn-primary" %> <% end %> Output Parameters: {"utf8"=>"?", "authenticity_token"=>"DjYvwkJeUhO06ds7bqshHsctS1M/Dth08rLlP2yQ7O0=", "restaurant"=>{"name"=>"The Pink Door", "job"=>{"shortname"=>"PD"}}, "commit"=>"Done"} The error i'm receiving is: ActiveModel::MassAssignmentSecurity::Error in RestaurantsController#create Cant mass-assign protected attributes: job Rails.root: /home/johnnyfive/Dropbox/Projects/sa Application Trace | Framework Trace | Full Trace app/controllers/restaurants_controller.rb:11:in `new' app/controllers/restaurants_controller.rb:11:in `create' Anyone have ANY clue how to get this to work? Thanks!

    Read the article

facebook twitter digg google delicious technorati stumbleupon myspace wordpress linkedin gmail igoogle windows live tumblr viadeo yahoo buzz yahoo mail yahoo bookmarks favorites email print

< Previous Page | 877 878 879 880 881 882 883 884 885 886 887 888  | Next Page >