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  • Discuss: PLs are characterised by which (iso)morphisms are implemented

    - by Yttrill
    I am interested to hear discussion of the proposition summarised in the title. As we know programming language constructions admit a vast number of isomorphisms. In some languages in some places in the translation process some of these isomorphisms are implemented, whilst others require code to be written to implement them. For example, in my language Felix, the isomorphism between a type T and a tuple of one element of type T is implemented, meaning the two types are indistinguishable (identical). Similarly, a tuple of N values of the same type is not merely isomorphic to an array, it is an array: the isomorphism is implemented by the compiler. Many other isomorphisms are not implemented for example there is an isomorphism expressed by the following client code: match v with | ((?x,?y),?z = x,(y,z) // Felix match v with | (x,y), - x,(y,z) (* Ocaml *) As another example, a type constructor C of int in Felix may be used directly as a function, whilst in Ocaml you must write a wrapper: let c x = C x Another isomorphism Felix implements is the elimination of unit values, including those in tuples: Felix can do this because (most) polymorphic values are monomorphised which can be done because it is a whole program analyser, Ocaml, for example, cannot do this easily because it supports separate compilation. For the same reason Felix performs type-class dispatch at compile time whilst Haskell passes around dictionaries. There are some quite surprising issues here. For example an array is just a tuple, and tuples can be indexed at run time using a match and returning a value of a corresponding sum type. Indeed, to be correct the index used is in fact a case of unit sum with N summands, rather than an integer. Yet, in a real implementation, if the tuple is an array the index is replaced by an integer with a range check, and the result type is replaced by the common argument type of all the constructors: two isomorphisms are involved here, but they're implemented partly in the compiler translation and partly at run time.

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  • Hibernate unable to instantiate default tuplizer - cannot find getter

    - by ZeldaPinwheel
    I'm trying to use Hibernate to persist a class that looks like this: public class Item implements Serializable, Comparable<Item> { // Item id private Integer id; // Description of item in inventory private String description; // Number of items described by this inventory item private int count; //Category item belongs to private String category; // Date item was purchased private GregorianCalendar purchaseDate; public Item() { } public Integer getId() { return id; } public void setId(Integer id) { this.id = id; } public String getDescription() { return description; } public void setDescription(String description) { this.description = description; } public int getCount() { return count; } public void setCount(int count) { this.count = count; } public String getCategory() { return category; } public void setCategory(String category) { this.category = category; } public GregorianCalendar getPurchaseDate() { return purchaseDate; } public void setPurchasedate(GregorianCalendar purchaseDate) { this.purchaseDate = purchaseDate; } My Hibernate mapping file contains the following: <property name="puchaseDate" type="java.util.GregorianCalendar"> <column name="purchase_date"></column> </property> When I try to run, I get error messages indicating there is no getter function for the purchaseDate attribute: 577 [main] INFO org.hibernate.connection.DriverManagerConnectionProvider - Using Hibernate built-in connection pool (not for production use!) 577 [main] INFO org.hibernate.connection.DriverManagerConnectionProvider - Hibernate connection pool size: 20 577 [main] INFO org.hibernate.connection.DriverManagerConnectionProvider - autocommit mode: false 592 [main] INFO org.hibernate.connection.DriverManagerConnectionProvider - using driver: com.mysql.jdbc.Driver at URL: jdbc:mysql://localhost:3306/home_inventory 592 [main] INFO org.hibernate.connection.DriverManagerConnectionProvider - connection properties: {user=root, password=****} 1078 [main] INFO org.hibernate.cfg.SettingsFactory - RDBMS: MySQL, version: 5.1.45 1078 [main] INFO org.hibernate.cfg.SettingsFactory - JDBC driver: MySQL-AB JDBC Driver, version: mysql-connector-java-5.1.12 ( Revision: ${bzr.revision-id} ) 1103 [main] INFO org.hibernate.dialect.Dialect - Using dialect: org.hibernate.dialect.MySQLDialect 1107 [main] INFO org.hibernate.engine.jdbc.JdbcSupportLoader - Disabling contextual LOB creation as JDBC driver reported JDBC version [3] less than 4 1109 [main] INFO org.hibernate.transaction.TransactionFactoryFactory - Using default transaction strategy (direct JDBC transactions) 1110 [main] INFO org.hibernate.transaction.TransactionManagerLookupFactory - No TransactionManagerLookup configured (in JTA environment, use of read-write or transactional second-level cache is not recommended) 1110 [main] INFO org.hibernate.cfg.SettingsFactory - Automatic flush during beforeCompletion(): disabled 1110 [main] INFO org.hibernate.cfg.SettingsFactory - Automatic session close at end of transaction: disabled 1110 [main] INFO org.hibernate.cfg.SettingsFactory - JDBC batch size: 15 1110 [main] INFO org.hibernate.cfg.SettingsFactory - JDBC batch updates for versioned data: disabled 1111 [main] INFO org.hibernate.cfg.SettingsFactory - Scrollable result sets: enabled 1111 [main] INFO org.hibernate.cfg.SettingsFactory - JDBC3 getGeneratedKeys(): enabled 1111 [main] INFO org.hibernate.cfg.SettingsFactory - Connection release mode: auto 1111 [main] INFO org.hibernate.cfg.SettingsFactory - Maximum outer join fetch depth: 2 1111 [main] INFO org.hibernate.cfg.SettingsFactory - Default batch fetch size: 1 1111 [main] INFO org.hibernate.cfg.SettingsFactory - Generate SQL with comments: disabled 1111 [main] INFO org.hibernate.cfg.SettingsFactory - Order SQL updates by primary key: disabled 1111 [main] INFO org.hibernate.cfg.SettingsFactory - Order SQL inserts for batching: disabled 1112 [main] INFO org.hibernate.cfg.SettingsFactory - Query translator: org.hibernate.hql.ast.ASTQueryTranslatorFactory 1113 [main] INFO org.hibernate.hql.ast.ASTQueryTranslatorFactory - Using ASTQueryTranslatorFactory 1113 [main] INFO org.hibernate.cfg.SettingsFactory - Query language substitutions: {} 1113 [main] INFO org.hibernate.cfg.SettingsFactory - JPA-QL strict compliance: disabled 1113 [main] INFO org.hibernate.cfg.SettingsFactory - Second-level cache: enabled 1113 [main] INFO org.hibernate.cfg.SettingsFactory - Query cache: disabled 1113 [main] INFO org.hibernate.cfg.SettingsFactory - Cache region factory : org.hibernate.cache.impl.NoCachingRegionFactory 1113 [main] INFO org.hibernate.cfg.SettingsFactory - Optimize cache for minimal puts: disabled 1114 [main] INFO org.hibernate.cfg.SettingsFactory - Structured second-level cache entries: disabled 1117 [main] INFO org.hibernate.cfg.SettingsFactory - Echoing all SQL to stdout 1118 [main] INFO org.hibernate.cfg.SettingsFactory - Statistics: disabled 1118 [main] INFO org.hibernate.cfg.SettingsFactory - Deleted entity synthetic identifier rollback: disabled 1118 [main] INFO org.hibernate.cfg.SettingsFactory - Default entity-mode: pojo 1118 [main] INFO org.hibernate.cfg.SettingsFactory - Named query checking : enabled 1118 [main] INFO org.hibernate.cfg.SettingsFactory - Check Nullability in Core (should be disabled when Bean Validation is on): enabled 1151 [main] INFO org.hibernate.impl.SessionFactoryImpl - building session factory org.hibernate.HibernateException: Unable to instantiate default tuplizer [org.hibernate.tuple.entity.PojoEntityTuplizer] at org.hibernate.tuple.entity.EntityTuplizerFactory.constructTuplizer(EntityTuplizerFactory.java:110) at org.hibernate.tuple.entity.EntityTuplizerFactory.constructDefaultTuplizer(EntityTuplizerFactory.java:135) at org.hibernate.tuple.entity.EntityEntityModeToTuplizerMapping.<init>(EntityEntityModeToTuplizerMapping.java:80) at org.hibernate.tuple.entity.EntityMetamodel.<init>(EntityMetamodel.java:323) at org.hibernate.persister.entity.AbstractEntityPersister.<init>(AbstractEntityPersister.java:475) at org.hibernate.persister.entity.SingleTableEntityPersister.<init>(SingleTableEntityPersister.java:133) at org.hibernate.persister.PersisterFactory.createClassPersister(PersisterFactory.java:84) at org.hibernate.impl.SessionFactoryImpl.<init>(SessionFactoryImpl.java:295) at org.hibernate.cfg.Configuration.buildSessionFactory(Configuration.java:1385) at service.HibernateSessionFactory.currentSession(HibernateSessionFactory.java:53) at service.ItemSvcHibImpl.generateReport(ItemSvcHibImpl.java:78) at service.test.ItemSvcTest.testGenerateReport(ItemSvcTest.java:226) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25) at java.lang.reflect.Method.invoke(Method.java:597) at junit.framework.TestCase.runTest(TestCase.java:164) at junit.framework.TestCase.runBare(TestCase.java:130) at junit.framework.TestResult$1.protect(TestResult.java:106) at junit.framework.TestResult.runProtected(TestResult.java:124) at junit.framework.TestResult.run(TestResult.java:109) at junit.framework.TestCase.run(TestCase.java:120) at junit.framework.TestSuite.runTest(TestSuite.java:230) at junit.framework.TestSuite.run(TestSuite.java:225) at org.eclipse.jdt.internal.junit.runner.junit3.JUnit3TestReference.run(JUnit3TestReference.java:130) at org.eclipse.jdt.internal.junit.runner.TestExecution.run(TestExecution.java:38) at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:467) at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:683) at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.run(RemoteTestRunner.java:390) at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.main(RemoteTestRunner.java:197) Caused by: java.lang.reflect.InvocationTargetException at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method) at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:39) at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:27) at java.lang.reflect.Constructor.newInstance(Constructor.java:513) at org.hibernate.tuple.entity.EntityTuplizerFactory.constructTuplizer(EntityTuplizerFactory.java:107) ... 29 more Caused by: org.hibernate.PropertyNotFoundException: Could not find a getter for puchaseDate in class domain.Item at org.hibernate.property.BasicPropertyAccessor.createGetter(BasicPropertyAccessor.java:328) at org.hibernate.property.BasicPropertyAccessor.getGetter(BasicPropertyAccessor.java:321) at org.hibernate.mapping.Property.getGetter(Property.java:304) at org.hibernate.tuple.entity.PojoEntityTuplizer.buildPropertyGetter(PojoEntityTuplizer.java:299) at org.hibernate.tuple.entity.AbstractEntityTuplizer.<init>(AbstractEntityTuplizer.java:158) at org.hibernate.tuple.entity.PojoEntityTuplizer.<init>(PojoEntityTuplizer.java:77) ... 34 more I'm new to Hibernate, so I don't know all the ins and outs, but I do have the getter and setter for the purchaseDate attribute. I don't know what I'm missing here - does anyone else? Thanks!

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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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  • Nested generator functions in python

    - by Yuval A
    Consider a tuple v = (a,b,c) and a generator function generate(x) which receives an item from the tuple and generates several options for each item. What is the pythonic way of generating a set of all the possible combinations of the result of generate(x) on each item in the tuple? I could do this: v = (a,b,c) for d in generate(v[0]): for e in generate(v[1]): for f in generate(v[2]): print d,e,f but that's just ugly, plus I need a generic solution.

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  • Test assertions for tuples with floats

    - by Space_C0wb0y
    I have a function that returns a tuple that, among others, contains a float value. Usually I use assertAlmostEquals to compare those, but this does not work with tuples. Also, the tuple contains other data-types as well. Currently I am asserting every element of the tuple individually, but that gets too much for a list of such tuples. Is there any good way to write assertions for such cases?

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  • Python: (sampling with replacement): efficient algorithm to extract the set of UNIQUE N-tuples from a set

    - by Homunculus Reticulli
    I have a set of items, from which I want to select DISSIMILAR tuples (more on the definition of dissimilar touples later). The set could contain potentially several thousand items, although typically, it would contain only a few hundreds. I am trying to write a generic algorithm that will allow me to select N items to form an N-tuple, from the original set. The new set of selected N-tuples should be DISSIMILAR. A N-tuple A is said to be DISSIMILAR to another N-tuple B if and only if: Every pair (2-tuple) that occurs in A DOES NOT appear in B Note: For this algorithm, A 2-tuple (pair) is considered SIMILAR/IDENTICAL if it contains the same elements, i.e. (x,y) is considered the same as (y,x). This is a (possible variation on the) classic Urn Problem. A trivial (pseudocode) implementation of this algorithm would be something along the lines of def fetch_unique_tuples(original_set, tuple_size): while True: # randomly select [tuple_size] items from the set to create first set # create a key or hash from the N elements and store in a set # store selected N-tuple in a container if end_condition_met: break I don't think this is the most efficient way of doing this - and though I am no algorithm theorist, I suspect that the time for this algorithm to run is NOT O(n) - in fact, its probably more likely to be O(n!). I am wondering if there is a more efficient way of implementing such an algo, and preferably, reducing the time to O(n). Actually, as Mark Byers pointed out there is a second variable m, which is the size of the number of elements being selected. This (i.e. m) will typically be between 2 and 5. Regarding examples, here would be a typical (albeit shortened) example: original_list = ['CAGG', 'CTTC', 'ACCT', 'TGCA', 'CCTG', 'CAAA', 'TGCC', 'ACTT', 'TAAT', 'CTTG', 'CGGC', 'GGCC', 'TCCT', 'ATCC', 'ACAG', 'TGAA', 'TTTG', 'ACAA', 'TGTC', 'TGGA', 'CTGC', 'GCTC', 'AGGA', 'TGCT', 'GCGC', 'GCGG', 'AAAG', 'GCTG', 'GCCG', 'ACCA', 'CTCC', 'CACG', 'CATA', 'GGGA', 'CGAG', 'CCCC', 'GGTG', 'AAGT', 'CCAC', 'AACA', 'AATA', 'CGAC', 'GGAA', 'TACC', 'AGTT', 'GTGG', 'CGCA', 'GGGG', 'GAGA', 'AGCC', 'ACCG', 'CCAT', 'AGAC', 'GGGT', 'CAGC', 'GATG', 'TTCG'] Select 3-tuples from the original list should produce a list (or set) similar to: [('CAGG', 'CTTC', 'ACCT') ('CAGG', 'TGCA', 'CCTG') ('CAGG', 'CAAA', 'TGCC') ('CAGG', 'ACTT', 'ACCT') ('CAGG', 'CTTG', 'CGGC') .... ('CTTC', 'TGCA', 'CAAA') ] [[Edit]] Actually, in constructing the example output, I have realized that the earlier definition I gave for UNIQUENESS was incorrect. I have updated my definition and have introduced a new metric of DISSIMILARITY instead, as a result of this finding.

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  • Python: (sampling with replacement): efficient algorithm to extract the set of DISSIMILAR N-tuples from a set

    - by Homunculus Reticulli
    I have a set of items, from which I want to select DISSIMILAR tuples (more on the definition of dissimilar touples later). The set could contain potentially several thousand items, although typically, it would contain only a few hundreds. I am trying to write a generic algorithm that will allow me to select N items to form an N-tuple, from the original set. The new set of selected N-tuples should be DISSIMILAR. A N-tuple A is said to be DISSIMILAR to another N-tuple B if and only if: Every pair (2-tuple) that occurs in A DOES NOT appear in B Note: For this algorithm, A 2-tuple (pair) is considered SIMILAR/IDENTICAL if it contains the same elements, i.e. (x,y) is considered the same as (y,x). This is a (possible variation on the) classic Urn Problem. A trivial (pseudocode) implementation of this algorithm would be something along the lines of def fetch_unique_tuples(original_set, tuple_size): while True: # randomly select [tuple_size] items from the set to create first set # create a key or hash from the N elements and store in a set # store selected N-tuple in a container if end_condition_met: break I don't think this is the most efficient way of doing this - and though I am no algorithm theorist, I suspect that the time for this algorithm to run is NOT O(n) - in fact, its probably more likely to be O(n!). I am wondering if there is a more efficient way of implementing such an algo, and preferably, reducing the time to O(n). Actually, as Mark Byers pointed out there is a second variable m, which is the size of the number of elements being selected. This (i.e. m) will typically be between 2 and 5. Regarding examples, here would be a typical (albeit shortened) example: original_list = ['CAGG', 'CTTC', 'ACCT', 'TGCA', 'CCTG', 'CAAA', 'TGCC', 'ACTT', 'TAAT', 'CTTG', 'CGGC', 'GGCC', 'TCCT', 'ATCC', 'ACAG', 'TGAA', 'TTTG', 'ACAA', 'TGTC', 'TGGA', 'CTGC', 'GCTC', 'AGGA', 'TGCT', 'GCGC', 'GCGG', 'AAAG', 'GCTG', 'GCCG', 'ACCA', 'CTCC', 'CACG', 'CATA', 'GGGA', 'CGAG', 'CCCC', 'GGTG', 'AAGT', 'CCAC', 'AACA', 'AATA', 'CGAC', 'GGAA', 'TACC', 'AGTT', 'GTGG', 'CGCA', 'GGGG', 'GAGA', 'AGCC', 'ACCG', 'CCAT', 'AGAC', 'GGGT', 'CAGC', 'GATG', 'TTCG'] # Select 3-tuples from the original list should produce a list (or set) similar to: [('CAGG', 'CTTC', 'ACCT') ('CAGG', 'TGCA', 'CCTG') ('CAGG', 'CAAA', 'TGCC') ('CAGG', 'ACTT', 'ACCT') ('CAGG', 'CTTG', 'CGGC') .... ('CTTC', 'TGCA', 'CAAA') ] [[Edit]] Actually, in constructing the example output, I have realized that the earlier definition I gave for UNIQUENESS was incorrect. I have updated my definition and have introduced a new metric of DISSIMILARITY instead, as a result of this finding.

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  • WCF methods sharing a dictionary

    - by YeomansLeo
    I'm creating a WCF Service Library and I have a question regarding thread-safety consuming a method inside this library, here is the full implementation that I have until now. namespace WCFConfiguration { [ServiceBehavior(InstanceContextMode = InstanceContextMode.PerCall, ConcurrencyMode = ConcurrencyMode.Single)] public class ConfigurationService : IConfigurationService { ConcurrentDictionary<Tuple<string,string>, string> configurationDictionary = new ConcurrentDictionary<Tuple<string,string>, string>(); public void Configuration(IEnumerable<Configuration> configurationSet) { Tuple<string, string> lookupStrings; foreach (var config in configurationSet) { lookupStrings = new Tuple<string, string>(config.BoxType, config.Size); configurationDictionary.TryAdd(lookupStrings, config.RowNumber); } } public void ScanReceived(string boxType, string size, string packerId = null) { } } } Imagine that I have a 10 values in my configurationDictionary and many people want to query this dictionary consuming ScanReceived method, are those 10 values be shared for each of the clients that request ScanReceived? Do I need to change my ServiceBehavior? The Configuration method is only consumed by one person by the way.

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  • Python server open all ports

    - by user1670178
    I am trying to open all ports using this code, why can I not create a loop to perform this function? http://www.kellbot.com/2010/02/tutorial-writing-a-tcp-server-in-python/ #!/usr/bin/python # This is server.py file ##server.py from socket import * #import the socket library n=1025 while n<1050: ##let's set up some constants HOST = '' #we are the host PORT = n #arbitrary port not currently in use ADDR = (HOST,PORT) #we need a tuple for the address BUFSIZE = 4096 #reasonably sized buffer for data ## now we create a new socket object (serv) ## see the python docs for more information on the socket types/flags serv = socket( AF_INET,SOCK_STREAM) ##bind our socket to the address serv.bind((ADDR)) #the double parens are to create a tuple with one element serv.listen(5) #5 is the maximum number of queued connections we'll allow serv = socket( AF_INET,SOCK_STREAM) ##bind our socket to the address serv.bind((ADDR)) #the double parens are to create a tuple with one element serv.listen(5) #5 is the maximum number of queued connections we'll allow print 'listening...' n=n+1 conn,addr = serv.accept() #accept the connection print '...connected!' conn.send('TEST') conn.close() How do I make this work so that I can specify input range and have the server open all ports up to 65535? #!/usr/bin/python # This is server.py file from socket import * #import the socket library startingPort=input("\nPlease enter starting port: ") startingPort=int(startingPort) #print startingPort def connection(): ## let's set up some constants HOST = '' #we are the host PORT = startingPort #arbitrary port not currently in use ADDR = (HOST,PORT) #we need a tuple for the address BUFSIZE = 4096 #reasonably sized buffer for data def socketObject(): ## now we create a new socket object (serv) serv = socket( AF_INET,SOCK_STREAM) def bind(): ## bind our socket to the address serv = socket( AF_INET,SOCK_STREAM) serv.bind((ADDR)) #the double parens are to create a tuple with one element serv.listen(5) #5 is the maximum number of queued connections we'll allow serv = socket( AF_INET,SOCK_STREAM) print 'listening...' def accept(): conn,addr = serv.accept() #accept the connection print '...connected!' conn.send('TEST') def close(): conn.close() ## Main while startingPort<65535: connection() socketObject() bind() accept() startingPort=startingPort+1

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  • When to use typedef?

    - by futlib
    I'm a bit confused about if and when I should use typedef in C++. I feel it's a balancing act between readability and clarity. Here's a code sample without any typedefs: int sum(std::vector<int>::const_iterator first, std::vector<int>::const_iterator last) { static std::map<std::tuple<std::vector<int>::const_iterator, std::vector<int>::const_iterator>, int> lookup_table; std::map<std::tuple<std::vector<int>::const_iterator, std::vector<int>::const_iterator>, int>::iterator lookup_it = lookup_table.find(lookup_key); if (lookup_it != lookup_table.end()) return lookup_it->second; ... } Pretty ugly IMO. So I'll add some typedefs within the function to make it look nicer: int sum(std::vector<int>::const_iterator first, std::vector<int>::const_iterator last) { typedef std::tuple<std::vector<int>::const_iterator, std::vector<int>::const_iterator> Lookup_key; typedef std::map<Lookup_key, int> Lookup_table; static Lookup_table lookup_table; Lookup_table::iterator lookup_it = lookup_table.find(lookup_key); if (lookup_it != lookup_table.end()) return lookup_it->second; ... } The code is still a bit clumsy, but I get rid of most nightmare material. But there's still the int vector iterators, this variant gets rid of those: typedef std::vector<int>::const_iterator Input_iterator; int sum(Input_iterator first, Input_iterator last) { typedef std::tuple<Input_iterator, Input_iterator> Lookup_key; typedef std::map<Lookup_key, int> Lookup_table; static Lookup_table lookup_table; Lookup_table::iterator lookup_it = lookup_table.find(lookup_key); if (lookup_it != lookup_table.end()) return lookup_it->second; ... } This looks clean, but is it still readable? When should I use a typedef? As soon as I have a nightmare type? As soon as it occurs more than once? Where should I put them? Should I use them in function signatures or keep them to the implementation?

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  • Real benefits of tcp TIME-WAIT and implications in production environment

    - by user64204
    SOME THEORY I've been doing some reading on tcp TIME-WAIT (here and there) and what I read is that it's a value set to 2 x MSL (maximum segment life) which keeps a connection in the "connection table" for a while to guarantee that, "before your allowed to create a connection with the same tuple, all the packets belonging to previous incarnations of that tuple will be dead". Since segments received (apart from SYN under specific circumstances) while a connection is either in TIME-WAIT or no longer existing would be discarded, why not close the connection right away? Q1: Is it because there is less processing involved in dealing with segments from old connections and less processing to create a new connection on the same tuple when in TIME-WAIT (i.e. are there performance benefits)? If the above explanation doesn't stand, the only reason I see the TIME-WAIT being useful would be if a client sends a SYN for a connection before it sends remaining segments for an old connection on the same tuple in which case the receiver would re-open the connection but then get bad segments and and would have to terminate it. Q2: Is this analysis correct? Q3: Are there other benefits to using TIME-WAIT? SOME PRACTICE I've been looking at the munin graphs on a production server that I administrate. Here is one: As you can see there are more connections in TIME-WAIT than ESTABLISHED, around twice as many most of the time, on some occasions four times as many. Q4: Does this have an impact on performance? Q5: If so, is it wise/recommended to reduce the TIME-WAIT value (and what to)? Q6: Is this ratio of TIME-WAIT / ESTABLISHED connections normal? Could this be related to malicious connection attempts?

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  • gcc built by crosstool-ng gives undefined reference

    - by netvope
    I've successfully built a toolchain using crosstool-ng with the default configuration named x86_64-unknown-linux-gnu. The documentation says: Using the toolchain is as simple as adding the toolchain's bin directory in your PATH, such as: export PATH="${PATH}:/your/toolchain/path/bin" and then using the target tuple to tell the build systems to use your toolchain: ./configure --target=your-target-tuple or make CC=your-target-tuple-gcc or make CROSS_COMPILE=your-target-tuple- and so on... I followed the instructions and attempted to build GNU tar (tar-1.25.tar.bz2) with the toolchain. The commands ./configure --target=x86_64-unknown-linux-gnu and make CROSS_COMPILE=x86_64-unknown-linux-gnu- do not work (the build will succeed, but it uses the host system's gcc). The command make CC=x86_64-unknown-linux-gnu-gcc works, but in the very last step when it tries to link, it returns errors like this: compare.o: In function `openat': /dev/shm/x-tools/x86_64-unknown-linux-gnu/x86_64-unknown-linux-gnu/sys-root/usr/include/bits/fcntl2.h:134: undefined reference to `__openat_2' What could be the problem? Was the toolchain not properly setup? Perhaps x86_64-unknown-linux-gnu-gcc is using the header files from the host system but could not find the libraries in the target's sys-root?

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  • Basic C question, concerning memory allocation and value assignment

    - by VHristov
    Hi there, I have recently started working on my master thesis in C that I haven't used in quite a long time. Being used to Java, I'm now facing all kinds of problems all the time. I hope someone can help me with the following one, since I've been struggling with it for the past two days. So I have a really basic model of a database: tables, tuples, attributes and I'm trying to load some data into this structure. Following are the definitions: typedef struct attribute { int type; char * name; void * value; } attribute; typedef struct tuple { int tuple_id; int attribute_count; attribute * attributes; } tuple; typedef struct table { char * name; int row_count; tuple * tuples; } table; Data is coming from a file with inserts (generated for the Wisconsin benchmark), which I'm parsing. I have only integer or string values. A sample row would look like: insert into table values (9205, 541, 1, 1, 5, 5, 5, 5, 0, 1, 9205, 10, 11, 'HHHHHHH', 'HHHHHHH', 'HHHHHHH'); I've "managed" to load and parse the data and also to assign it. However, the assignment bit is buggy, since all values point to the same memory location, i.e. all rows look identical after I've loaded the data. Here is what I do: char value[10]; // assuming no value is longer than 10 chars int i, j, k; table * data = (table*) malloc(sizeof(data)); data->name = "table"; data->row_count = number_of_lines; data->tuples = (tuple*) malloc(number_of_lines*sizeof(tuple)); tuple* current_tuple; for(i=0; i<number_of_lines; i++) { current_tuple = &data->tuples[i]; current_tuple->tuple_id = i; current_tuple->attribute_count = 16; // static in our system current_tuple->attributes = (attribute*) malloc(16*sizeof(attribute)); for(k = 0; k < 16; k++) { current_tuple->attributes[k].name = attribute_names[k]; // for int values: current_tuple->attributes[k].type = DB_ATT_TYPE_INT; // write data into value-field int v = atoi(value); current_tuple->attributes[k].value = &v; // for string values: current_tuple->attributes[k].type = DB_ATT_TYPE_STRING; current_tuple->attributes[k].value = value; } // ... } While I am perfectly aware, why this is not working, I can't figure out how to get it working. I've tried following things, none of which worked: memcpy(current_tuple->attributes[k].value, &v, sizeof(int)); This results in a bad access error. Same for the following code (since I'm not quite sure which one would be the correct usage): memcpy(current_tuple->attributes[k].value, &v, 1); Not even sure if memcpy is what I need here... Also I've tried allocating memory, by doing something like: current_tuple->attributes[k].value = (int *) malloc(sizeof(int)); only to get "malloc: * error for object 0x100108e98: incorrect checksum for freed object - object was probably modified after being freed." As far as I understand this error, memory has already been allocated for this object, but I don't see where this happened. Doesn't the malloc(sizeof(attribute)) only allocate the memory needed to store an integer and two pointers (i.e. not the memory those pointers point to)? Any help would be greatly appreciated! Regards, Vassil

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  • make_tuple with boost::python under Visual Studio 9

    - by celil
    Trying to build the following simple example #include <boost/python.hpp> using namespace boost::python; tuple head_and_tail(object sequence) { return make_tuple(sequence[0],sequence[-1]); } available here, I end up with this compilation error under Visual Studio 9 error C2668: 'boost::python::make_tuple' : ambiguous call to overloaded function 1> C:\Program Files\boost_1_42_0\boost/python/detail/make_tuple.hpp(22): could be 'boost::python::tuple boost::python::make_tuple<boost::python::api::object_item,boost::python::api::object_item>(const A0 &,const A1 &)' 1> with 1> [ 1> A0=boost::python::api::object_item, 1> A1=boost::python::api::object_item 1> ] 1> C:\Program Files\boost_1_42_0\boost/tuple/detail/tuple_basic.hpp(802): or 'boost::tuples::tuple<T0,T1,T2,T3,T4,T5,T6,T7,T8,T9> boost::tuples::make_tuple<boost::python::api::object_item,boost::python::api::object_item>(const T0 &,const T1 &)' [found using argument-dependent lookup] 1> with 1> [ 1> T0=boost::python::api::proxy<boost::python::api::item_policies>, 1> T1=boost::python::api::proxy<boost::python::api::item_policies>, 1> T2=boost::tuples::null_type, 1> T3=boost::tuples::null_type, 1> T4=boost::tuples::null_type, 1> T5=boost::tuples::null_type, 1> T6=boost::tuples::null_type, 1> T7=boost::tuples::null_type, 1> T8=boost::tuples::null_type, 1> T9=boost::tuples::null_type 1> ] Is this a bug in boost::python, or am I doing something wrong? How can I get the above program to compile?

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  • algorithm for python itertools.permutations

    - by zaharpopov
    Can someone please explain algorithm for itertools.permutations routine in Python standard lib 2.6? I see its code in the documentation but don't undestand why it work? Thanks Code is: def permutations(iterable, r=None): # permutations('ABCD', 2) --> AB AC AD BA BC BD CA CB CD DA DB DC # permutations(range(3)) --> 012 021 102 120 201 210 pool = tuple(iterable) n = len(pool) r = n if r is None else r if r > n: return indices = range(n) cycles = range(n, n-r, -1) yield tuple(pool[i] for i in indices[:r]) while n: for i in reversed(range(r)): cycles[i] -= 1 if cycles[i] == 0: indices[i:] = indices[i+1:] + indices[i:i+1] cycles[i] = n - i else: j = cycles[i] indices[i], indices[-j] = indices[-j], indices[i] yield tuple(pool[i] for i in indices[:r]) break else: return

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  • Does throwing an exception in an EvalFunc pig UDF skip just that line, or stop completely?

    - by Daniel Huckstep
    I have a User Defined Function (UDF) written in Java to parse lines in a log file and return information back to pig, so it can do all the processing. It looks something like this: public abstract class Foo extends EvalFunc<Tuple> { public Foo() { super(); } public Tuple exec(Tuple input) throws IOException { try { // do stuff with input } catch (Exception e) { throw WrappedIOException.wrap("Error with line", e); } } } My question is: if it throws the IOException, will it stop completely, or will it return results for the rest of the lines that don't throw an exception? Example: I run this in pig REGISTER myjar.jar DEFINE Extractor com.namespace.Extractor(); logs = LOAD '$IN' USING TextLoader AS (line: chararray); events = FOREACH logs GENERATE FLATTEN(Extractor(line)); With this input: 1.5 7 "Valid Line" 1.3 gghyhtt Inv"alid line"" I throw an exceptioN!! 1.8 10 "Valid Line 2" Will it process the two lines and will 'logs' have 2 tuples, or will it just die in a fire?

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  • how to extract elements from a list in python ?

    - by Stefano Borini
    I feel suddenly uneasy of not being able to perform this operation easily. It could be that I'm tired, or that there's really no way (google didn't help), but... if you have a list in python, and want to extract element at indices say 1, 2 and 5 into a new list, how do you do ? This is how I did it, but I'm not very satisfied >>> a [10, 11, 12, 13, 14, 15] >>> [x[1] for x in enumerate(a) if x[0] in [1,2,5]] [11, 12, 15] any better way ? more in general, given a tuple with indices, how to use this tuple to extract the corresponding elements from a list, eventually with duplication (e.g. tuple (1,1,2,1,5) produces [11,11,12,11,15] )

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  • How can I implement the same behavior as Dictionary.TryGetValue

    - by pblasucci
    So, given then following code type MyClass () = let items = Dictionary<string,int>() do items.Add ("one",1) items.Add ("two",2) items.Add ("three",3) member this.TryGetValue (key,value) = items.TrygetValue (key,value) let c = MyClass () let d = Dictionary<string,int> () d.Add ("one",1) d.Add ("two",2) d.Add ("three",3) And the following test code let r1,v1 = d.TryGetValue "one" let r2,v2 = c.TryGetValue "one" The r1,v1 line works fine. The r2,v2 line bombs; complaining c.TryGetValue must be given a tuple. Interestingly, in each line the signature of TryGetValue is different. How can I get my custom implementation to exhibit the same behavior as the BCL version? Or, asked another way, since F# has (implicitly) the concept of tuple parameters, curried parameters, and BCL parameters, and I know how to distinguish between curried and tuple-style, how can I force the third style (a la BCL methods)? Let me know if this is unclear.

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  • Apply function to one element of a list in Python

    - by user189637
    I'm looking for a concise and functional style way to apply a function to one element of a tuple and return the new tuple, in Python. For example, for the following input: inp = ("hello", "my", "friend") I would like to be able to get the following output: out = ("hello", "MY", "friend") I came up with two solutions which I'm not satisfied with. One uses a higher-order function. def apply_at(arr, func, i): return arr[0:i] + [func(arr[i])] + arr[i+1:] apply_at(inp, lambda x: x.upper(), 1) One uses list comprehensions (this one assumes the length of the tuple is known). [(a,b.upper(),c) for a,b,c in [inp]][0] Is there a better way? Thanks!

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  • What are "named tuples" in Python?

    - by Denilson Sá
    Reading the changes in Python 3.1, I found something... unexpected: The sys.version_info tuple is now a named tuple: I never heard about named tuples before, and I thought elements could either be indexed by numbers (like in tuples and lists) or by keys (like in dicts). I never expected they could be indexed both ways. Thus, my questions are: What are named tuples? How to use them? Why/when should I use named tuples instead of normal tuples? Why/when should I use normal tuples instead of named tuples? Is there any kind of "named list" (a mutable version of the named tuple)?

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  • Lifetime of implicitly casted temporaries

    - by Answeror
    I have seen this question. It seems that regardless of the cast, the temporary object(s) will "survive" until the fullexpression evaluated. But in the following scenario: void foo(boost::tuple<const double&> n) { printf("%lf\n", n.get<0>()); } int main() { foo(boost::tuple<const double&>(2));//#1 foo(boost::make_tuple(2));//#2 return 0; } 1 run well, but 2 do not. And MSVC gave me a warning about 2: "reference member is initialized to a temporary that doesn't persist after the constructor exits" Now I am wondering why they both make a temporary "double" object and pass it to boost::tuple<const double&> and only 2 failed.

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  • : for displaying all elements in a multidimensional array in python 3.1.

    - by Leif Andersen
    I have a multidimensional array in python like: arr = [['foo', 1], ['bar',2]] Now, if I want to print out everything in the array, I could do: print(arr[:][:]) Or I could also just do print(arr). However, If I only wanted to print out the first element of each box (for arr, that would be 'foo', 'bar'), I would imagine I would do something like: print(arr[:][0]) however, that just prints out the first data blog (['foo', 1]), also, I tried reversing it (just in case): print(arr[0][:]) and I got the same thing. So, is there anyway that I can get it to print the first element in each tuple (other than: for tuple in arr: print(tuple[0]) )? Thanks.

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  • Feedback on implementation of function which compares integer signs in Python.

    - by John Magistr
    Hi all. I've made a small function which, given a tuple, compares if all elements in this tuple is of the same sign. E.g., tuple = [-1, -4, -6, -8] is good, while [-1, -4, 12, -8] is bad. I am not sure I've made the smartest implementation, so I know this is the place to ask. def check_consistent_categories(queryset): try: first_item = queryset[0].amount if first_item < 0: for item in queryset: if item > 0: return False return True else: for item in queryset: if item < 0: return False return True except: return False

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  • Python C API return more than one value / object

    - by Grisu
    I got the following problem. I have written a C-Extension to Python to interface a self written software library. Unfortunately I need to return two values from the C function where the last one is optional. In Python the equivalent is def func(x,y): return x+y, x-y test = func(13,4) #only the first value is used In my C extension I use return Py_BuildValue("ii",x+y,x-y); which results in a tuple. If I now try to access the return value from Python via test2 = cfunc(13,4) print(test2) I got a tuple instead of only the first return value. How is possible to build the same behavior as in Python from C Extension?

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  • Reordering Variadic Parameters

    - by void-pointer
    I have come across the need to reorder a variadic list of parameters that is supplied to the constructor of a struct. After being reordered based on their types, the parameters will be stored as a tuple. My question is how this can be done so that a modern C++ compiler (e.g. g++-4.7) will not generate unnecessary load or store instructions. That is, when the constructor is invoked with a list of parameters of variable size, it efficiently pushes each parameter into place based on an ordering over the parameters' types. Here is a concrete example. Assume that the base type of every parameter (without references, rvalue references, pointers, or qualifiers) is either char, int, or float. How can I make it so that all the parameters of base type char appear first, followed by all of those of base type int (which leaves the parameters of base type float last). The relative order in which the parameters were given should not be violated within sublists of homogeneous base type. Example: foo::foo() is called with arguments float a, char&& b, const float& c, int&& d, char e. The tuple tupe is std::tuple<char, char, int, float, float>, and it is constructed like so: tuple_type{std::move(b), e, std::move(d), a, c}. Consider the struct defined below, and assume that the metafunction deduce_reordered_tuple_type is already implemented. How would you write the constructor so that it works as intended? If you think that the code for deduce_reodered_tuple_type, would be useful to you, I can provide it; it's a little long. template <class... Args> struct foo { // Assume that the metafunction deduce_reordered_tuple_type is defined. typedef typename deduce_reordered_tuple_type<Args...>::type tuple_type; tuple_type t_; foo(Args&&... args) : t_{reorder_and_forward_parameters<Args>(args)...} {} }; Edit 1 The technique I describe above does have applications in mathematical frameworks that make heavy use of expression templates, variadic templates, and metaprogramming in order to perform aggressive inlining. Suppose that you wish to define an operator that takes the product of several expressions, each of which may be passed by reference, reference to const, or rvalue reference. (In my case, the expressions are conditional probability tables and the operation is the factor product, but something like matrix multiplication works suitably as well.) You need access to the data provided by each expression in order to evaluate the product. Consequently, you must move the expressions passed as rvalue references, copy the expressions passed by reference to const, and take the addresses of expressions passed by reference. Using the technique I describe above now poses several benefits. Other expressions can use uniform syntax to access data elements from this expression, since all of the heavy-lifting metaprogramming work is done beforehand, within the class. We can save stack space by grouping the pointers together and storing the larger expressions towards the end of the tuple. Implementing certain types of queries becomes much easier (e.g. check whether any of the pointers stored in the tuple aliases a given pointer). Thank you very much for your help!

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