生成文件中意外标记附近的语法错误

Question

I'm trying to create a template in Makefile to reuse Python virtualenv. in Makefile I define:

ENV_CREATE ?= $(shell python3 -m virtualenv venv) and in target:

set_up:
    $(ENV_CREATE) ; \
    . venv/bin/activate

As a result of Makefiule target execution I'm getting

/bin/sh: -c: line 0: syntax error near unexpected token `('
/bin/sh: -c: line 0: `echo created virtual environment CPython3.7.9.final.0-64 in 333ms   creator CPython3Posix(dest=/Users/marian/Work/git/sigma/sphere/sphere-data-platform/venv, clear=False, no_vcs_ignore=False, global=False)   seeder FromAppData(download=False, pip=bundle, setuptools=bundle, wheel=bundle, via=copy, app_data_dir=/Users/marian/Library/Application Support/virtualenv)     added seed packages: pip==21.1.2, setuptools==57.0.0, wheel==0.36.2   activators BashActivator,CShellActivator,FishActivator,PowerShellActivator,PythonActivator,XonshActivator ; . venv/bin/activate    python3 -m pip install -r requirements.txt -r requirements-dev.txt ; '
make: *** [setup] Error 2

What am I doing wrong?

Answer 1

In ENV_CREATE ?= $(shell...) the right hand side seems to be evaluated non-recursively (that is, immediately). So the ENV_CREATE variable is assigned the result of this shell script: [created ... .

In your recipe you use the expansion of this make variable ( $(ENV_CREATE) ) as shell syntax, while it is not shell syntax, it is the output message of python3 -m virtualenv venv .

There is absolutely no point in using the shell make function in a recipe which is already... a shell script. Try:

ENV_CREATE ?= python3 -m virtualenv venv

set_up:
    $(ENV_CREATE) ; \
    . venv/bin/activate

Make will expand the recipe before passing it to the shell. So what will be passed to the shell is:

python3 -m virtualenv venv ; . venv/bin/activate

But note that sourcing ( . venv/bin/activate ) as the last command of a recipe will probably not do anything useful.

Answer 2

Why not just use another target?

venv:
      python3 -m virtualenv venv


set_up: venv
        . venv/bin/activate

This way, you only create the virtual environment if it doesn't already exist.

Answer 3

Managed to find the best way. Seems like i don't need a $(shell python 3...) construction. I have defined variable with Make commands(no shell) and injected it as one-liner:

ENV_CREATE := python3 -m virtualenv venv ; . venv/bin/activate ;

setup:
$(ENV_CREATE) python3 -m pip install -r requirements.txt

now I can re-use $(ENV_CREATE) in other targets the same way(integration tests, unit tests, etc.)