Suppressing Errors in Variables -- and Checking Available Commands

[ethanmsl]

Large Goal: Do conditional logic on presence or absence of commands. (e.g. if my user doesn't have a build system present or the right version of an interpreter installed I want to warn them or switch commands)

Small Goal: Get variables to ignore errors.

This fails:

# fails because type returns non-0 on command not found
cmd_present := if "nothere not found" == `type nothere` {"true"} else {"false"}

This is a hacky workaround:

# succeeds because last command doesn't error, but pollute stderr
cmd_present := if "nothere not found" == `type nothere | xargs echo` {"true"} else {"false"}

But besides being incredibly hacky, it also pollutes stderr on every command.

e.g.

> just anything
sh: line 0: type: nothere: not found
...

---

So: can we suppress errors for variables?
Other good patterns for checking what commands are installed?

[ethanmsl]

EDIT:
These work well for getting the conditional logic.
Basically using a workaround for error-code and then using a command that doesn't print to stderr on not-found

Just:

POETRY_COMMAND := `command -v poetry 2>/dev/null || echo "NOT_FOUND"`
ASDF_COMMAND := `command -v asdf 2>/dev/null || echo "NOT_FOUND"`
MADEUPJUNK_COMMAND := `command -v madeupjunk 2>/dev/null || echo "NOT_FOUND"`

and this would be similar syntax for Make:

HAS_POETRY := $(shell command -v poetry 2> /dev/null)
HAS_ASDF := $(shell command -v asdf 2> /dev/null)
HAS_MADEUPJUNK := $(shell command -v madeupjunk 2> /dev/null)

Still curious on other approaches to local and general problem though!