Re: [ft-devel] Patch to fix the ttsubpix implementation

[Behdad Esfahbod]

On 13-01-17 11:03 PM, Dmitry Timoshkov wrote:
> Behdad Esfahbod <address@hidden> wrote:
> 
>>>> Guys, I'm not a hardcore C coder, and don't know about private RAM
>>>> allocation per-process, and how that's impacted by putting structs
>>>> inside of .c files instead of .h files.  Of course, I'm willing to
>>>> understand why that's the case, I just don't necessarily know some
>>>> of that stuff.  So, likely all code that I write is going to have
>>>> the potential of being implemented more efficiently by people with
>>>> more experience in coding.  I don't really want to burden you guys
>>>> with "babying" me through the best way to implement code, but if you
>>>> can nudge me in the right direction sometimes that would be helpful.
>>
>> If you have some time to read, this is a good place to start:
>>
>>   http://www.akkadia.org/drepper/dsohowto.pdf
> 
> Reading that paper made my head hurt :) It's full of descriptions of
> various tricks and jumps through the hoops how to avoid limitations of
> dynamic libraries implementation under Linux which is based on old,
> questionable and inefficient design. This really has nothing to do
> with the problem David has fixed.

There's an expression that programmers use: "think low-level, write
high-level".  The point being that to write good code one has to understand
how the compiler and the machine work, but then write high-level code that
translates to good machine code.  What David found was indeed different:
defining variables in a header file is a basic mistake of C / C++ programming,
but when you get past that, making sure that your variable don't end up
consuming private per-process memory (specially when dealing with strings) has
a lot to do with understanding how the linker works, and what is dealt with in
the mentioned paper.

-- 
behdad
http://behdad.org/