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 | Posted by Jonathan M Davis |  Permalink Reply |
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Jonathan M Davis 
| They've made my life way easier on a number of projects lately - particularly involving parsing. For instance, I've got some code for parsing H.264 headers that looks like this
mixin(parseUEV!("chroma_format_idc"));
if(chroma_format_idc == 3)
{
mixin(parseU!("separate_colour_plane_flag", 1));
}
mixin(parseUEV!("bit_depth_luma_minus8"));
mixin(parseUEV!("bit_depth_chroma_minus8"));
mixin(parseU!("qpprime_y_zero_transform_bypass_flag", 1));
mixin(parseU!("seq_scaling_matrix_present_flag", 1));
I can simply pass a variable name as a string to a template (along with the number of bits to parse if relevant), and it'll generate a string that once mixed in will declare that variable, parse out bits from a buffer (with a name that the template knows) using whatever algorithm or function is associated with that template, and assign the result to that variable. And of course that variable is usable throughout the rest of the scope that the mixin was used in. On top of that, all I have to do is alter the few templates that I use to generate the strings, and I can make it print out the value, or append it to another buffer, or assign it to a corresponding field in a struct, so on and so forth. It saves quite a bit of code duplication, and makes it _really_ easy to change what a whole ton of lines of code do. And the code is just as efficient had I typed it all out myself, since it's just copy-pasted in place. This is fantastic!
I've got a variety of such mixins in a variety of projects, and they really help simplify the code. This is one feature in D that's really made my life easier. So, a huge thanks to whoever though it up (probably Walter, but I really don't know)!
- Jonathan M Davis
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