In Python can I call the main of an imported module

Question

In Python I have a module myModule py where I define a few functions and a main    which takes a few command line arguments    I usually call this main   from a bash script  Now  I would like to put everything into a small package  so I thought that maybe I could turn my simple bash script into a Python script and put it in the package   So  how do I actually call the main   function of myModule py from the main   function of MyFormerBashScript py  Can I even do that  How do I pass any arguments to it

User · Answer

Assuming you are trying to pass the command line arguments as well   import sys import myModule   def main          this will just pass all of the system arguments as is     myModule main  sys argv         all the argv but the script name     myModule main  sys argv 1

User · Answer

Martijen s answer makes sense  but it was missing something crucial that may seem obvious to others but was hard for me to figure out   In the version where you use argparse  you need to have this line in the main body   args   parser parse args args    Normally when you are using argparse just in a script you just write  args   parser parse args     and parse args find the arguments from the command line  But in this case the main function does not have access to the command line arguments  so you have to tell argparse what the arguments are   Here is an example   import argparse import sys  def x x center  y center       print  X center    x center     print  Y center    y center  def main args       parser   argparse ArgumentParser description  Do something        parser add argument  -x    --xcenter   type float  default  2  required False      parser add argument  -y    --ycenter   type float  default  4  required False      args   parser parse args args      x args xcenter  args ycenter   if   name         main         main sys argv 1      Assuming you named this mytest py To run it you can either do any of these from the command line  python   mytest py -x 8 python   mytest py -x 8 -y 2 python   mytest py    which returns respectively  X center  8 0 Y center  4   or  X center  8 0 Y center  2 0   or  X center  2 Y center  4   Or if you want to run from another python script you can do  import mytest mytest main   -x   7   -y   6       which returns   X center  7 0 Y center  6 0

User · Answer

It depends  If the main code is protected by an if as in   if   name         main            main code      then no  you can t make Python execute that because you can t influence the automatic variable   name     But when all the code is in a function  then might be able to  Try  import myModule  myModule main     This works even when the module protects itself with a   all      from myModule import   might not make main visible to you  so you really need to import the module itself

User · Answer

The answer I was searching for was answered here  How to use python argparse with args other than sys argv   If main py and parse args   is written in this way  then the parsing can be done nicely    main py import argparse def parse args        parser   argparse ArgumentParser description         parser add argument  --input   default  my input txt       return parser  def main args       print args input   if   name         main         parser   parse args       args   parser parse args       main args    Then you can call main   and parse arguments with parser parse args   --input    foobar txt    to it in another python script     temp py from main import main  parse args parser   parse args   args   parser parse args       note the square bracket   to overwrite default  use parser parse args   --input    foobar txt    print args    Namespace input  my input txt   main args

User · Answer

It s just a function  Import it and call it   import myModule  myModule main     If you need to parse arguments  you have two options    Parse them in main    but pass in sys argv as a parameter  all code below in the same module myModule    def main args         parse arguments using optparse or argparse or what have you  if   name         main         import sys     main sys argv 1      Now you can import and call myModule main   arg1    arg2    arg3    from other another module  Have main   accept parameters that are already parsed  again all code in the myModule module    def main foo  bar  baz  spam          run with already parsed arguments  if   name         main         import sys       parse sys argv 1   using optparse or argparse or what have you     main foovalue  barvalue    dictofoptions    and import and call myModule main foovalue  barvalue  baz  ham   elsewhere and passing in python arguments as needed    The trick here is to detect when your module is being used as a script  when you run a python file as the main script  python filename py  no import statement is being used  so python calls that module    main     But if that same filename py code is treated as a module  import filename   then python uses that as the module name instead  In both cases the variable   name   is set  and testing against that tells you how your code was run

User · Answer

I had the same need using argparse too   The thing is parse args function of an argparse ArgumentParser object instance implicitly takes its arguments by default from sys args  The work around  following Martijn line  consists of making that explicit  so you can change the arguments you pass to parse args as desire   def main args         some stuff     parser   argparse ArgumentParser         some other stuff     parsed args   parser parse args args        more stuff with the args  if   name         main         import sys     main sys argv 1      The key point is passing args to parse args function  Later  to use the main  you just do as Martijn tell

[python] In Python, can I call the main() of an imported module?

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