Configuring Meta-Programming

Dieter Schön dieter@REDACTED
Sat Jan 30 12:27:10 CET 2021

Hi Mark,

so instead of each user configures his/her environment, you will have to 
build a bespoke

app for each user.

You will have to know the desired configuration for each user, and build 
a custom version

for each variant.

The technical part is relatively easy, I think. The parameters can be 
implemented as

-define(ParamX, ValueY).

Maybe add some -ifdef, if the configuration is complex.

And, from a CM perspective, I would definitely have everything in 
version-controlled files.

No ad-hoc commandline switch-triggered artifacts.

Also, for runtime introspection, add a function which outputs the 
configuration parameters

of the module.

 From my experience, in a commercial environment,

you should be most concerned how to be able to reliable and reproducible

build a version. And to be able to track which versions are in use where.

kind regards,


On 29.01.21 15:25, Mark S wrote:
> Hello,
> I'm looking for advice on how to configure code generated at compile 
> time.  My current solution reads the configuration values from a file, 
> but the feedback I received indicates that requiring users to create 
> and maintain a config file, in order to use this library, will at the 
> very least, severely limit its usefulness.
> Is there another way to introduce configuration values at compile 
> time?  Is there a library you can point me to, that has resolved the 
> same issue differently?
> Specifically, I created code that generates a module, containing a 
> custom Cyclic Redundancy Check (CRC) calculation function that 
> utilizes a CRC look-up table.  Creating the function and the look-up 
> table requires specifying the bit width, polynomial, initial value, 
> final XOR value, and whether the input and output values are reflected 
> or not.
> To generate the code module, I used Ulf Wiger's parse_trans library. 
> In particular, ct_expand:term() to generate the look-up table, and 
> codegen:gen_module() to generate the code and finally calling 
> merl:compile() to compile the abstract syntax tree, generated by 
> gen_module().
> Thanks,
> Mark Sebald

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