Re: [PATCH] docs: point out that locals should be defined at the top of a block of code
On Thu, Jul 09, 2020 at 06:41:21PM -0400, Laine Stump wrote: > Although we have nothing in make syntax-check to enforce this, and > apparently there are places where it isn't the case (according to > Dan), we should discourage the practice of defining new variables in > the middle of a block of code. > > https://www.redhat.com/archives/libvir-list/2020-July/msg00433.html > Signed-off-by: Laine Stump > --- > docs/coding-style.rst | 38 ++ > 1 file changed, 38 insertions(+) > > diff --git a/docs/coding-style.rst b/docs/coding-style.rst > index 03b89c86e5..b9b4a16987 100644 > --- a/docs/coding-style.rst > +++ b/docs/coding-style.rst > @@ -541,6 +541,44 @@ diligent about this, when you see a non-const pointer, > you're > guaranteed that it is used to modify the storage it points to, or > it is aliased to another pointer that is. > > +Defining Local Variables > + > + > +Always define local variables at the top of the block in which they > +are used (before any pure code). Although modern C compilers allow > +defining a local variable in the middle of a block of code, this > +practice can lead to bugs, and must be avoided in all libvirt > +code. (As indicated in these examples, it is okay to initialize > +variables where they are defined, even if the initialization involves > +calling another function.) > + > +:: > + > + GOOD: > +int > +Bob(char *loblaw) Since we are nitpicking I don't think we allow the first letter of the function name to be uppercase. :) Reviewed-by: Pavel Hrdina signature.asc Description: PGP signature
Re: [PATCH] docs: point out that locals should be defined at the top of a block of code
On Thu, Jul 09, 2020 at 06:41:21PM -0400, Laine Stump wrote: > Although we have nothing in make syntax-check to enforce this, and > apparently there are places where it isn't the case (according to > Dan), we should discourage the practice of defining new variables in > the middle of a block of code. > > https://www.redhat.com/archives/libvir-list/2020-July/msg00433.html > Signed-off-by: Laine Stump > --- > docs/coding-style.rst | 38 ++ > 1 file changed, 38 insertions(+) Reviewed-by: Daniel P. Berrangé Regards, Daniel -- |: https://berrange.com -o-https://www.flickr.com/photos/dberrange :| |: https://libvirt.org -o-https://fstop138.berrange.com :| |: https://entangle-photo.org-o-https://www.instagram.com/dberrange :|
Re: [PATCH] docs: point out that locals should be defined at the top of a block of code
On Thu, 2020-07-09 at 18:41 -0400, Laine Stump wrote: > +Defining Local Variables > + > + > +Always define local variables at the top of the block in which they > +are used (before any pure code). Although modern C compilers allow > +defining a local variable in the middle of a block of code, this > +practice can lead to bugs, and must be avoided in all libvirt > +code. (As indicated in these examples, it is okay to initialize > +variables where they are defined, even if the initialization involves > +calling another function.) The parentheses around the last sentence are unnecessary, please drop them. > + GOOD: > +int > +Bob(char *loblaw) > +{ > +int x; > +int y = lawBlog(loblaw); I believe this should be int y = lawBlog(); but note that I haven't compile-tested this alternative version. > + BAD: > +int > +Bob(char *loblaw) > +{ > +int x; > +int y = lawBlog(loblaw); > + > +x = y + 20; > + > +char *z = NULL; <=== Please add // in front of the ASCII arrow. It's pretty weird how we use C++-style comments throughout our style guide, at the same time as *the style guide itself* instructs developers to use C-style comments instead, but addressing that is a job for another patch :) With the nits fixed, Reviewed-by: Andrea Bolognani -- Andrea Bolognani / Red Hat / Virtualization
[PATCH] docs: point out that locals should be defined at the top of a block of code
Although we have nothing in make syntax-check to enforce this, and apparently there are places where it isn't the case (according to Dan), we should discourage the practice of defining new variables in the middle of a block of code. https://www.redhat.com/archives/libvir-list/2020-July/msg00433.html Signed-off-by: Laine Stump --- docs/coding-style.rst | 38 ++ 1 file changed, 38 insertions(+) diff --git a/docs/coding-style.rst b/docs/coding-style.rst index 03b89c86e5..b9b4a16987 100644 --- a/docs/coding-style.rst +++ b/docs/coding-style.rst @@ -541,6 +541,44 @@ diligent about this, when you see a non-const pointer, you're guaranteed that it is used to modify the storage it points to, or it is aliased to another pointer that is. +Defining Local Variables + + +Always define local variables at the top of the block in which they +are used (before any pure code). Although modern C compilers allow +defining a local variable in the middle of a block of code, this +practice can lead to bugs, and must be avoided in all libvirt +code. (As indicated in these examples, it is okay to initialize +variables where they are defined, even if the initialization involves +calling another function.) + +:: + + GOOD: +int +Bob(char *loblaw) +{ +int x; +int y = lawBlog(loblaw); +char *z = NULL; + +x = y + 20; +... +} + + BAD: +int +Bob(char *loblaw) +{ +int x; +int y = lawBlog(loblaw); + +x = y + 20; + +char *z = NULL; <=== +... +} + Attribute annotations - -- 2.25.4