What is an alternative to execfile in Python 3

Question

It seems they canceled in Python 3 all the easy way to quickly load a script by removing execfile     Is there an obvious alternative I m missing

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Note that the above pattern will fail if you re using PEP-263 encoding declarations that aren t ascii or utf-8  You need to find the encoding of the data  and encode it  correctly before handing it to exec     class python3Execfile object       def  get file encoding self  filename           with open filename   rb   as fp              try                  return tokenize detect encoding fp readline  0              except SyntaxError                  return  utf-8       def my execfile filename           globals    file       filename         with open filename   r   encoding self  get file encoding filename   as fp              contents   fp read           if not contents endswith   n                  http   bugs python org issue10204             contents      n          exec contents  globals  globals

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You are just supposed to read the file and exec the code yourself  2to3 current replaces  execfile  somefile py   global vars  local vars    as  with open  somefile py   as f      code   compile f read     somefile py    exec       exec code  global vars  local vars     The compile call isn t strictly needed  but it associates the filename with the code object making debugging a little easier    See    http   docs python org release 2 7 3 library functions html execfile http   docs python org release 3 2 3 library functions html compile http   docs python org release 3 2 3 library functions html exec

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You could write your own function   def xfile afile  globalz None  localz None       with open afile   r   as fh          exec fh read    globalz  localz    If you really needed to

User · Answer

You could write your own function   def xfile afile  globalz None  localz None       with open afile   r   as fh          exec fh read    globalz  localz    If you really needed to

User · Answer

You are just supposed to read the file and exec the code yourself  2to3 current replaces  execfile  somefile py   global vars  local vars    as  with open  somefile py   as f      code   compile f read     somefile py    exec       exec code  global vars  local vars     The compile call isn t strictly needed  but it associates the filename with the code object making debugging a little easier    See    http   docs python org release 2 7 3 library functions html execfile http   docs python org release 3 2 3 library functions html compile http   docs python org release 3 2 3 library functions html exec

User · Answer

As suggested on the python-dev mailinglist recently  the runpy module might be a viable alternative  Quoting from that message      https   docs python org 3 library runpy html runpy run path  import runpy file globals   runpy run path  file py      There are subtle differences to execfile    run path always creates a new namespace  It executes the code as a module  so there is no difference between globals and locals  which is why there is only a init globals argument   The globals are returned   execfile executed in the current namespace or the given namespace  The semantics of locals and globals  if given  were similar to locals and globals inside a class definition  run path can not only execute files  but also eggs and directories  refer to its documentation for details

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According to the documentation  instead of   execfile    filename      Use  exec open    filename   read      See    What   s New In Python 3 0

User · Answer

Avoid exec   if you can  For most applications  it s cleaner to make use of Python s import system  This function uses built-in importlib to execute a file as an actual module  from importlib import util  def load file as module name  location       spec   util spec from file location name  location      module   util module from spec spec      spec loader exec module module      return module  Usage example Let s have a file foo py  def hello        return  hi from module   print  imported from     file     as     name     And import it as a regular module   gt  gt  gt  mod   load file as module  mymodule      foo py   imported from  tmp foo py as mymodule  gt  gt  gt  mod hello   hi from module   gt  gt  gt  type mod   lt class  module  gt   Advantages This approach doesn t pollute namespaces or messes with your  PATH whereas exec   runs code directly in the context of the current function  potentially causing name collisions  Also  module attributes like   file   and   name   will be set correctly  and code locations are preserved  So  if you ve attached a debugger or if the module raises an exception  you will get usable tracebacks  Note that one minor difference from static imports is that the module gets imported  executed  every time you run load file as module    and not just once as with the import keyword

User · Answer

Note that the above pattern will fail if you re using PEP-263 encoding declarations that aren t ascii or utf-8  You need to find the encoding of the data  and encode it  correctly before handing it to exec     class python3Execfile object       def  get file encoding self  filename           with open filename   rb   as fp              try                  return tokenize detect encoding fp readline  0              except SyntaxError                  return  utf-8       def my execfile filename           globals    file       filename         with open filename   r   encoding self  get file encoding filename   as fp              contents   fp read           if not contents endswith   n                  http   bugs python org issue10204             contents      n          exec contents  globals  globals

User · Answer

I m just a newbie here so maybe it s pure luck if I found this    After trying to run a script from the interpreter prompt     with the command      execfile  filename py     for which I got a  NameError  name  execfile  is not defined  I tried a very basic       import filename   it worked well  -   I hope this can be helpful and thank you all for the great hints  examples and all those masterly commented pieces of code that are a great inspiration for newcomers     I use Ubuntu 16 014 LTS x64   Python 3 5 2  default  Nov 17 2016  17 05 23    GCC 5 4 0 20160609  on linux

User · Answer

Avoid exec   if you can  For most applications  it s cleaner to make use of Python s import system  This function uses built-in importlib to execute a file as an actual module  from importlib import util  def load file as module name  location       spec   util spec from file location name  location      module   util module from spec spec      spec loader exec module module      return module  Usage example Let s have a file foo py  def hello        return  hi from module   print  imported from     file     as     name     And import it as a regular module   gt  gt  gt  mod   load file as module  mymodule      foo py   imported from  tmp foo py as mymodule  gt  gt  gt  mod hello   hi from module   gt  gt  gt  type mod   lt class  module  gt   Advantages This approach doesn t pollute namespaces or messes with your  PATH whereas exec   runs code directly in the context of the current function  potentially causing name collisions  Also  module attributes like   file   and   name   will be set correctly  and code locations are preserved  So  if you ve attached a debugger or if the module raises an exception  you will get usable tracebacks  Note that one minor difference from static imports is that the module gets imported  executed  every time you run load file as module    and not just once as with the import keyword

User · Answer

This one is better  since it takes the globals and locals from the caller   import sys def execfile filename  globals None  locals None       if globals is None          globals   sys  getframe 1  f globals     if locals is None          locals   sys  getframe 1  f locals     with open filename   r   as fh          exec fh read     n   globals  locals

User · Answer

You are just supposed to read the file and exec the code yourself  2to3 current replaces  execfile  somefile py   global vars  local vars    as  with open  somefile py   as f      code   compile f read     somefile py    exec       exec code  global vars  local vars     The compile call isn t strictly needed  but it associates the filename with the code object making debugging a little easier    See    http   docs python org release 2 7 3 library functions html execfile http   docs python org release 3 2 3 library functions html compile http   docs python org release 3 2 3 library functions html exec

User · Answer

If the script you want to load is in the same directory than the one you run  maybe  import  will do the job    If you need to dynamically import code the built-in function    import   and the module imp are worth looking at    gt  gt  gt  import sys  gt  gt  gt  sys path      path to script     sys path  gt  gt  gt    import    test    lt module  test  from   path to script test pyc  gt   gt  gt  gt    import    test   run    Hello world     test py   def run            return  Hello world     If you re using Python 3 1 or later  you should also take a look at importlib

User · Answer

Also  while not a pure Python solution  if you re using IPython  as you probably should anyway   you can do    run  path to filename py   Which is equally easy

User · Answer

I m just a newbie here so maybe it s pure luck if I found this    After trying to run a script from the interpreter prompt     with the command      execfile  filename py     for which I got a  NameError  name  execfile  is not defined  I tried a very basic       import filename   it worked well  -   I hope this can be helpful and thank you all for the great hints  examples and all those masterly commented pieces of code that are a great inspiration for newcomers     I use Ubuntu 16 014 LTS x64   Python 3 5 2  default  Nov 17 2016  17 05 23    GCC 5 4 0 20160609  on linux

User · Answer

If the script you want to load is in the same directory than the one you run  maybe  import  will do the job    If you need to dynamically import code the built-in function    import   and the module imp are worth looking at    gt  gt  gt  import sys  gt  gt  gt  sys path      path to script     sys path  gt  gt  gt    import    test    lt module  test  from   path to script test pyc  gt   gt  gt  gt    import    test   run    Hello world     test py   def run            return  Hello world     If you re using Python 3 1 or later  you should also take a look at importlib

User · Answer

You are just supposed to read the file and exec the code yourself  2to3 current replaces  execfile  somefile py   global vars  local vars    as  with open  somefile py   as f      code   compile f read     somefile py    exec       exec code  global vars  local vars     The compile call isn t strictly needed  but it associates the filename with the code object making debugging a little easier    See    http   docs python org release 2 7 3 library functions html execfile http   docs python org release 3 2 3 library functions html compile http   docs python org release 3 2 3 library functions html exec

User · Answer

You could write your own function   def xfile afile  globalz None  localz None       with open afile   r   as fh          exec fh read    globalz  localz    If you really needed to

User · Answer

This one is better  since it takes the globals and locals from the caller   import sys def execfile filename  globals None  locals None       if globals is None          globals   sys  getframe 1  f globals     if locals is None          locals   sys  getframe 1  f locals     with open filename   r   as fh          exec fh read     n   globals  locals

User · Answer

While exec open  filename   read    is often given as an alternative to execfile  filename    it misses important details that execfile supported   The following function for Python3 x is as close as I could get to having the same behavior as executing a file directly  That matches running python  path to somefile py   def execfile filepath  globals None  locals None       if globals is None          globals          globals update              file     filepath             name        main                with open filepath   rb   as file          exec compile file read    filepath   exec    globals  locals     execute the file execfile   path to somefile py     Notes    Uses binary reading to avoid encoding issues Guaranteed to close the file  Python3 x warns about this  Defines   main    some scripts depend on this to check if they are loading as a module or not for eg  if   name         main    Setting   file   is nicer for exception messages and some scripts use   file   to get the paths of other files relative to them  Takes optional globals  amp  locals arguments  modifying them in-place as execfile does - so you can access any variables defined by reading back the variables after running  Unlike Python2 s execfile this does not modify the current namespace by default  For that you have to explicitly pass in globals    amp  locals

User · Answer

As suggested on the python-dev mailinglist recently  the runpy module might be a viable alternative  Quoting from that message      https   docs python org 3 library runpy html runpy run path  import runpy file globals   runpy run path  file py      There are subtle differences to execfile    run path always creates a new namespace  It executes the code as a module  so there is no difference between globals and locals  which is why there is only a init globals argument   The globals are returned   execfile executed in the current namespace or the given namespace  The semantics of locals and globals  if given  were similar to locals and globals inside a class definition  run path can not only execute files  but also eggs and directories  refer to its documentation for details

User · Answer

Also  while not a pure Python solution  if you re using IPython  as you probably should anyway   you can do    run  path to filename py   Which is equally easy

User · Answer

If the script you want to load is in the same directory than the one you run  maybe  import  will do the job    If you need to dynamically import code the built-in function    import   and the module imp are worth looking at    gt  gt  gt  import sys  gt  gt  gt  sys path      path to script     sys path  gt  gt  gt    import    test    lt module  test  from   path to script test pyc  gt   gt  gt  gt    import    test   run    Hello world     test py   def run            return  Hello world     If you re using Python 3 1 or later  you should also take a look at importlib

User · Answer

You could write your own function   def xfile afile  globalz None  localz None       with open afile   r   as fh          exec fh read    globalz  localz    If you really needed to

User · Answer

While exec open  filename   read    is often given as an alternative to execfile  filename    it misses important details that execfile supported   The following function for Python3 x is as close as I could get to having the same behavior as executing a file directly  That matches running python  path to somefile py   def execfile filepath  globals None  locals None       if globals is None          globals          globals update              file     filepath             name        main                with open filepath   rb   as file          exec compile file read    filepath   exec    globals  locals     execute the file execfile   path to somefile py     Notes    Uses binary reading to avoid encoding issues Guaranteed to close the file  Python3 x warns about this  Defines   main    some scripts depend on this to check if they are loading as a module or not for eg  if   name         main    Setting   file   is nicer for exception messages and some scripts use   file   to get the paths of other files relative to them  Takes optional globals  amp  locals arguments  modifying them in-place as execfile does - so you can access any variables defined by reading back the variables after running  Unlike Python2 s execfile this does not modify the current namespace by default  For that you have to explicitly pass in globals    amp  locals

User · Answer

According to the documentation  instead of   execfile    filename      Use  exec open    filename   read      See    What   s New In Python 3 0

User · Answer

Here s what I had  file is already assigned to the path to the file with the source code in both examples    execfile file    Here s what I replaced it with   exec compile open file  read    file   exec      My favorite part  the second version works just fine in both Python 2 and 3  meaning it s not necessary to add in version dependent logic

User · Answer

If the script you want to load is in the same directory than the one you run  maybe  import  will do the job    If you need to dynamically import code the built-in function    import   and the module imp are worth looking at    gt  gt  gt  import sys  gt  gt  gt  sys path      path to script     sys path  gt  gt  gt    import    test    lt module  test  from   path to script test pyc  gt   gt  gt  gt    import    test   run    Hello world     test py   def run            return  Hello world     If you re using Python 3 1 or later  you should also take a look at importlib

User · Answer

Here s what I had  file is already assigned to the path to the file with the source code in both examples    execfile file    Here s what I replaced it with   exec compile open file  read    file   exec      My favorite part  the second version works just fine in both Python 2 and 3  meaning it s not necessary to add in version dependent logic

[python] What is an alternative to execfile in Python 3?

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