David Aldrich wrote:
> Hi Peter
>
> Thanks very much for your reply. I have added one more question below.
>
>> The straightforward approach is to pass a list or tuple:
>>
>> def build(build_options=()):
>> subprocess_check_call(("make",) + build_options)
>>
>> build(("flagA=true", "flagB=true"))
>
> This looks fine - I am trying it.
>
> I would like to display on the console the entire make command, so I have
> done this:
>
> def build(build_options=()):
> make_command = 'make '.join(map(build_options))
> print('Build command: ' + make_command)
> subprocess.check_call(("make",)+build_options)
>
> but I get error:
>
> make_command = 'make '.join(map(build_options))
> TypeError: map() must have at least two arguments.
>
> What would be the correct way to concatenate and display the elements in
> the tuple please?
Hm, what do you expect map() to achieve? And "make " is not really the
string you want as a separator...
You can join the strings in build_options with
>>> build_options = "foo", "bar", "baz"
>>> " ".join(build_options)
'foo bar baz'
>>> "make " + " ".join(build_options)
'make foo bar baz'
But you shouldn't do this as you have already learnt that spaces do not
separate arguments; in fact by default check_call() doesn't even use the
shell. An example to drive the point home:
>>> from subprocess import check_call
>>> check_call(["python3", "-c", "import sys; print(sys.argv[1:])", "foo",
"bar"])
['foo', 'bar']
0
>>> check_call(["python3", "-c", "import sys; print(sys.argv[1:])", "foo
bar"])
['foo bar']
Both invocations would appear to issue the same command in your debugging
print() call. list2cmdline() does a bit better; it resembles the command
issued if the shell were used:
>>> print(subprocess.list2cmdline(["make"] + build_options))
make foo "bar baz"
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