number of arguments a function takes

[Elaine Jackson]

Suppose one of the arguments of a function f_1 is another function f_2. Can f_1
access the number of arguments taken by f_2? (I'm writing a little script to
automate the construction of logical truth-tables.) Thanks.

Peace

[Aahz]

In article <CSaSb.329909$ts4.189798@pd7tw3no>,
Elaine Jackson <el***************@home.com> wrote:

Suppose one of the arguments of a function f_1 is another function
f_2. Can f_1 access the number of arguments taken by f_2? (I'm writing
a little script to automate the construction of logical truth-tables.)

In theory, yes (because of Python's introspection capabilities). In
practice, you're likely to want to choose a different mechanism that
doesn't require that information. If you tell us more about your actual
problem, we may be able to point you in a better direction.
--
Aahz (aa**@pythoncraft.com) <*> http://www.pythoncraft.com/

"The joy of coding Python should be in seeing short, concise, readable
classes that express a lot of action in a small amount of clear code --
not in reams of trivial code that bores the reader to death." --GvR

[Duncan Booth]

"Elaine Jackson" <el***************@home.com> wrote in
news:CSaSb.329909$ts4.189798@pd7tw3no:

Suppose one of the arguments of a function f_1 is another function
f_2. Can f_1 access the number of arguments taken by f_2? (I'm
writing a little script to automate the construction of logical
truth-tables.) Thanks.

Look at the inspect module, in particular you probably want
inspect.getargspec:

import inspect
def f(a,b): pass inspect.getargspec(f) (['a', 'b'], None, None, None) help(inspect.getargspec) Help on function getargspec in module inspect:

getargspec(func)
Get the names and default values of a function's arguments.

A tuple of four things is returned: (args, varargs, varkw, defaults).
'args' is a list of the argument names (it may contain nested lists).
'varargs' and 'varkw' are the names of the * and ** arguments or None.
'defaults' is an n-tuple of the default values of the last n arguments.

[Elaine Jackson]

Exactly what I was looking for. Thank you very much.

"Duncan Booth" <[e-mail]> wrote in message
news:Xn***************************@127.0.0.1...
| "Elaine Jackson" <el***************@home.com> wrote in
| news:CSaSb.329909$ts4.189798@pd7tw3no:
|
| > Suppose one of the arguments of a function f_1 is another function
| > f_2. Can f_1 access the number of arguments taken by f_2? (I'm
| > writing a little script to automate the construction of logical
| > truth-tables.) Thanks.
|
| Look at the inspect module, in particular you probably want
| inspect.getargspec:
|
| >>> import inspect
| >>> def f(a,b): pass
|
| >>> inspect.getargspec(f)
| (['a', 'b'], None, None, None)
| >>> help(inspect.getargspec)
| Help on function getargspec in module inspect:
|
| getargspec(func)
| Get the names and default values of a function's arguments.
|
| A tuple of four things is returned: (args, varargs, varkw, defaults).
| 'args' is a list of the argument names (it may contain nested lists).
| 'varargs' and 'varkw' are the names of the * and ** arguments or None.
| 'defaults' is an n-tuple of the default values of the last n arguments.
|
| >>>

[Corey Coughlin]

"Elaine Jackson" <el***************@home.com> wrote in message news:<YVbSb.319671$JQ1.192347@pd7tw1no>...

Exactly what I was looking for. Thank you very much.

"Duncan Booth" <[e-mail]> wrote in message
news:Xn***************************@127.0.0.1...
| "Elaine Jackson" <el***************@home.com> wrote in
| news:CSaSb.329909$ts4.189798@pd7tw3no:
|
| > Suppose one of the arguments of a function f_1 is another function
| > f_2. Can f_1 access the number of arguments taken by f_2? (I'm
| > writing a little script to automate the construction of logical
| > truth-tables.) Thanks.
|
| Look at the inspect module, in particular you probably want
| inspect.getargspec:
|
| >>> import inspect
| >>> def f(a,b): pass

| >>> inspect.getargspec(f)
(['a', 'b'], None, None, None)
| >>> help(inspect.getargspec)
| Help on function getargspec in module inspect:
|
| getargspec(func)
| Get the names and default values of a function's arguments.
|
| A tuple of four things is returned: (args, varargs, varkw, defaults).
| 'args' is a list of the argument names (it may contain nested lists).
| 'varargs' and 'varkw' are the names of the * and ** arguments or None.
| 'defaults' is an n-tuple of the default values of the last n arguments.
|
| >>>

So you're working on a truth table program? I have a truth table
object I did for my own application, more focused on finding
input/output transitions in arbitrary truth tables, but if you're
interested, let me know. Regardless, are you working on something
that will ultimately become public? If so, be sure to announce it
when you're done, I'd love to have a look. Especially if you're doing
anything with functional simplification, my object can return a simple
SOP function for a table (reducing out unused inputs is also an
option) but they can get kind of lengthy for complicated functions.
And if you need any other help, be sure to let me know!

[Elaine Jackson]

I think you're expectations of this are a little high. It's just something I did
for amusement while I was drinking my coffee this morning. Anyway, here it is.
And yes, I'd be very interested to see your code.

Peace (code follows)

NEG = lambda A: not A
CONJ = lambda *args: False not in args
DISJ = lambda *args: True in args
IMPL = lambda A,B: (not A) or B
EQUIV = lambda A,B: (A and B) or (not A and not B)

def truthTable(boolFunct):
assignmentList = lambda numArgs: (numArgs==0 and [[]]) or \
reduce(list.__add__,[[X+[False],X+[True]] for X in
assignmentList(numArgs-1)])
import inspect
numArgs=len(inspect.getargspec(boolFunct)[0])
for assignment in assignmentList(numArgs):
print assignment," : ",boolFunct(*assignment)

## EXAMPLE:
f = lambda x,y,z: DISJ(CONJ(x,y),NEG(z))
truthTable(f)
"Corey Coughlin" <co************@attbi.com> wrote in message
news:a8**************************@posting.google.c om...
| "Elaine Jackson" <el***************@home.com> wrote in message
news:<YVbSb.319671$JQ1.192347@pd7tw1no>...
| > Exactly what I was looking for. Thank you very much.
| >
| > "Duncan Booth" <[e-mail]> wrote in message
| > news:Xn***************************@127.0.0.1...
| > | "Elaine Jackson" <el***************@home.com> wrote in
| > | news:CSaSb.329909$ts4.189798@pd7tw3no:
| > |
| > | > Suppose one of the arguments of a function f_1 is another function
| > | > f_2. Can f_1 access the number of arguments taken by f_2? (I'm
| > | > writing a little script to automate the construction of logical
| > | > truth-tables.) Thanks.
| > |
| > | Look at the inspect module, in particular you probably want
| > | inspect.getargspec:
| > |
| > | >>> import inspect
| > | >>> def f(a,b): pass
| >
| > | >>> inspect.getargspec(f)
| > (['a', 'b'], None, None, None)
| > | >>> help(inspect.getargspec)
| > | Help on function getargspec in module inspect:
| > |
| > | getargspec(func)
| > | Get the names and default values of a function's arguments.
| > |
| > | A tuple of four things is returned: (args, varargs, varkw, defaults).
| > | 'args' is a list of the argument names (it may contain nested lists).
| > | 'varargs' and 'varkw' are the names of the * and ** arguments or None.
| > | 'defaults' is an n-tuple of the default values of the last n
arguments.
| > |
| > | >>>
|
| So you're working on a truth table program? I have a truth table
| object I did for my own application, more focused on finding
| input/output transitions in arbitrary truth tables, but if you're
| interested, let me know. Regardless, are you working on something
| that will ultimately become public? If so, be sure to announce it
| when you're done, I'd love to have a look. Especially if you're doing
| anything with functional simplification, my object can return a simple
| SOP function for a table (reducing out unused inputs is also an
| option) but they can get kind of lengthy for complicated functions.
| And if you need any other help, be sure to let me know!