Is there a way to have a local version of a header file?

> for an embedded project built inside the Arduino IDE, (alternate firmware
> for a home automation project) there is a need to set a number of parameters
> that we really don't want in the main repo (wifi network IDs/passwords)
>
> right now, we have these things set as #defines in a header file.
>
> We need to distribute a base version of this file for new people to get
> started.
>
> Is there any way to have git define a file in such a way that if it doesn't
> exist in the worktree it gets populated, but if it does exist it doesn't get
> overwritten? (as I type this, I'm thinking a trigger may work, but we need
> it to work on Linux, Windows and OSX)
>
> Any thoughts on a sane way to handle this situation?

> On Sat, Mar 18, 2017 at 3:29 PM, David Lang <david@lang.hm> wrote:
>> for an embedded project built inside the Arduino IDE, (alternate firmware
>> for a home automation project) there is a need to set a number of parameters
>> that we really don't want in the main repo (wifi network IDs/passwords)
>>
>> right now, we have these things set as #defines in a header file.
>>
>> We need to distribute a base version of this file for new people to get
>> started.
>>
>> Is there any way to have git define a file in such a way that if it doesn't
>> exist in the worktree it gets populated, but if it does exist it doesn't get
>> overwritten? (as I type this, I'm thinking a trigger may work, but we need
>> it to work on Linux, Windows and OSX)
>>
>> Any thoughts on a sane way to handle this situation?
>
> There's no sane way to do what you're describing without renaming the file.
>
> But the sanest way to do this is to have a config.h.example
>
> Then you have "/config.h" in the .gitignore file.
>
> And you tell the users to copy the *.example file to *.h, and your
> program then includes the *.h file.
>
> If you wanted to provide defaults you could just #include the
> config.h.example first, so #defines in the *.h file would clobber
> those in the *.example.

> On Sat, 18 Mar 2017, Ævar Arnfjörð Bjarmason wrote:
>
>> On Sat, Mar 18, 2017 at 3:29 PM, David Lang <david@lang.hm> wrote:
>>>
>>> for an embedded project built inside the Arduino IDE, (alternate firmware
>>> for a home automation project) there is a need to set a number of
>>> parameters
>>> that we really don't want in the main repo (wifi network IDs/passwords)
>>>
>>> right now, we have these things set as #defines in a header file.
>>>
>>> We need to distribute a base version of this file for new people to get
>>> started.
>>>
>>> Is there any way to have git define a file in such a way that if it
>>> doesn't
>>> exist in the worktree it gets populated, but if it does exist it doesn't
>>> get
>>> overwritten? (as I type this, I'm thinking a trigger may work, but we
>>> need
>>> it to work on Linux, Windows and OSX)
>>>
>>> Any thoughts on a sane way to handle this situation?
>>
>>
>> There's no sane way to do what you're describing without renaming the
>> file.
>>
>> But the sanest way to do this is to have a config.h.example
>>
>> Then you have "/config.h" in the .gitignore file.
>>
>> And you tell the users to copy the *.example file to *.h, and your
>> program then includes the *.h file.
>>
>> If you wanted to provide defaults you could just #include the
>> config.h.example first, so #defines in the *.h file would clobber
>> those in the *.example.
>
>
> That's what we currently have (user_config.h and user_config_override.h)
>
> I was hoping to not have the situation where downloading and trying to
> compile will complain about a missing include file (if the users don't copy
> user_config_override_example.h to user_config_override.h) while letting us
> do a .gitignore on user_config_override.h
>
> for many people using this project, this is the first time they have ever
> compiled anything, and we have the typical set of people not reading
> instructions :-/
>
> Darn, I was hoping that the scenario of needing to have a config file
> provided in the repo, while not overwriting local changes to it was common
> enough that there were some tricks available. This is a little harder as the
> running code doesn't have a filesystem so we are limited to what we can do
> in the compiler and git (no makefile even, the Arduino folks consider that
> too complicated, it just slurps up all .ino files in a directory and
> compiles them)

> Ævar Arnfjörð Bjarmason <avarab@gmail.com> writes:
>
>> There might be some way I haven't thought of, in particular maybe you
>> can use gitattributes to define a custom diff/merge driver that always
>> reports no changes, or some ways to (ab)use the index to make git
>> ignore any changes to the file.
>
> Why does this have to be so difficult?
>
> Ship a config.h.sample file, have a Makefile rule that is forced to
> run before any compilation happens that checks if config.h exists
> and then created it if missing by copying config.h.sample over, and
> then all other source files can include config.h without having to
> know anything about config.h.sample's existence.
>
> Did I miss something?

>> Ship a config.h.sample file, have a Makefile rule that is forced to
>> run before any compilation happens that checks if config.h exists
>> and then created it if missing by copying config.h.sample over, and
>> then all other source files can include config.h without having to
>> know anything about config.h.sample's existence.
>>
>> Did I miss something?
>
> There is no makefile with the arduino IDE/build system :-(

> David Lang <david@lang.hm> writes:
>
>>> Ship a config.h.sample file, have a Makefile rule that is forced to
>>> run before any compilation happens that checks if config.h exists
>>> and then created it if missing by copying config.h.sample over, and
>>> then all other source files can include config.h without having to
>>> know anything about config.h.sample's existence.
>>>
>>> Did I miss something?
>>
>> There is no makefile with the arduino IDE/build system :-(
>
> How does "the build system" you want to make it work with actually
> work?  Is it incapable of "compiling" a "source file" into an
> "object file" that happens to be a text using an arbitrary
> "compiler"?
>
> I was hoping that readers are imaginative enough to replace Makefile
> with whatever way things are normally built with when reading my
> message, and the reader can just replace "source file" with
> "config.h.sample", "compiler" with "test -f config.h || cat
> config.h.sample >config.h" and "object file" with "config.h".

> I'd just provide a .sample and tell people what to do with it in the
> README. The alternative is to provide config.h as is and tell people
> to use "git update-index --assume-unchanged" immediately after cloning
> to ignore changes to the file, but this is prone to people
> accidentally committing credentials.

> David Lang <david@lang.hm> writes:
>
>>> Ship a config.h.sample file, have a Makefile rule that is forced to
>>> run before any compilation happens that checks if config.h exists
>>> and then created it if missing by copying config.h.sample over, and
>>> then all other source files can include config.h without having to
>>> know anything about config.h.sample's existence.
>>>
>>> Did I miss something?
>>
>> There is no makefile with the arduino IDE/build system :-(
>
> How does "the build system" you want to make it work with actually
> work?  Is it incapable of "compiling" a "source file" into an
> "object file" that happens to be a text using an arbitrary
> "compiler"?

> I was hoping that readers are imaginative enough to replace Makefile
> with whatever way things are normally built with when reading my
> message, and the reader can just replace "source file" with
> "config.h.sample", "compiler" with "test -f config.h || cat
> config.h.sample >config.h" and "object file" with "config.h".
>