[17/20] git-p4: compare to singletons with "is" and "is not"

Commit Message

Joel Holdsworth Jan. 12, 2022, 1:46 p.m. UTC

PEP8 recommends that comparisons with singletons such as None should be
done with "is" and "is not", and never equality operators.

This guideline is described here:
https://www.python.org/dev/peps/pep-0008/#programming-recommendations

Signed-off-by: Joel Holdsworth <[e-mail]>
---
 git-p4.py | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

Comments

Eric Sunshine Jan. 12, 2022, 7:54 p.m. UTC | #1

On Wed, Jan 12, 2022 at 8:47 AM Joel Holdsworth <[e-mail]> wrote:
> PEP8 recommends that comparisons with singletons such as None should be
> done with "is" and "is not", and never equality operators.
>
> This guideline is described here:
> https://www.python.org/dev/peps/pep-0008/#programming-recommendations
>
> Signed-off-by: Joel Holdsworth <[e-mail]>
> ---
> diff --git a/git-p4.py b/git-p4.py
> @@ -930,7 +930,7 @@ def p4Where(depotPath):
>              if data[:space] == depotPath:
>                  output = entry
>                  break
> -    if output == None:
> +    if not output:
>          return ""

This changes semantics, doesn't it? It will now return "" for None,
False, and "". Is this change intentional? To match the intent of the
original, I would have expected it to be written:

    if output is None:
        return ""

but, having glanced at the larger context, I suppose the new semantics
may be okay(?).

>  def parseRevision(ref):
> @@ -4497,7 +4497,7 @@ def main():
>      if cmd.needsGit:
> -        if cmd.gitdir == None:
> +        if not cmd.gitdir:
>              cmd.gitdir = os.path.abspath(".git")

Same question/observation as above. In order to save reviewers some
time, perhaps the commit message could say something about why the
semantic change is safe and/or desirable.

Patch

diff --git a/git-p4.py b/git-p4.py
index 0159e35adc..2a3409ebd2 100755
--- a/git-p4.py
+++ b/git-p4.py
@@ -930,7 +930,7 @@  def p4Where(depotPath):
             if data[:space] == depotPath:
                 output = entry
                 break
-    if output == None:
+    if not output:
         return ""
     if output["code"] == "error":
         return ""
@@ -952,7 +952,7 @@  def currentGitBranch():
 
 
 def isValidGitDir(path):
-    return git_dir(path) != None
+    return git_dir(path) is not None
 
 
 def parseRevision(ref):
@@ -4497,7 +4497,7 @@  def main():
     global verbose
     verbose = cmd.verbose
     if cmd.needsGit:
-        if cmd.gitdir == None:
+        if not cmd.gitdir:
             cmd.gitdir = os.path.abspath(".git")
             if not isValidGitDir(cmd.gitdir):
                 # "rev-parse --git-dir" without arguments will try $PWD/.git