meta-template | : sparkles : Automagically convert Nunjucks

Without utilizing the nonstandard‡ Scalar_Storage_Order clause in recent releases of GNAT, how can, say, the IPv4 header be portably represented via Record Representation Clause(s) in conjunction with any combination of any other language features, so that “the same” code works on both little-endian and big-endian processors but be emitted on the wire (e.g., via, say, the payload of an Ethernet frame) in what IETF calls network byte order (which is IETF's fancy name for big-endian). In C, “the same” code could utilize preprocessor macros to perform byte-swapping on little-endian processors, but be a no-op on big-endian processors, but standard Ada has no preprocessor. In C++, “the same” code could utilize meta-template programming (MTP) to perform byte-swapping on little-endian processors, but be a no-op on big-endian processors, but standard Ada lacks MTP.

(Btw, much the same issue arises in a device driver when a big-endian processor interfaces with a little-endian peripheral IC's memory-mapped register, or vice versa: little-endian processor interfaces with a big-endian IC's memory-mapped register.)

I'm trying to write a generic erase_if method that can be used on any container type to remove elements given a predicate. It should either use the erase-remove-idiom if the container allows it, or loop through the container and call the erase method. I also just want to provide the container itself, not the begin and end iterator separatly. That shall be handled by the method.

However I can't get the meta-template to work to distinguish between the two cases through SFINAE. I'm trying to check whether the method std::remove_if (or std::remove) would be well defined for a given type, but the value is either true for both vector and map (in which case the code won't compile) or false for both of them. I'm quite new to template meta-programming, so is there something I'm missing? Or maybe there's another, better solution?

Below is my example code:

I have following struct:

Jörg's answer to this question nicely delineates between "normal" templates (what the question refers to, perhaps erroneously, as generics) which operate on data and meta templates which operate on a program. Jörg then wisely mentions that programs are data so its really all one and the same. That said, meta-templates are still a different beast. Where do normal templates end and meta templates begin?

The best test I can come up with is if a template's arguments are exclusively class or typename the template is "normal" and meta otherwise. Is this test correct?

We have set of different web application projects, which is delivered by Teamcity to different environments. At this moment, we are doing all-in-one builds: compile, package and deploy at once; all based on a templates.

Now I am investigating a way to separate concenrs: one build tests and produces package, another - delivers. Naturally, both builds are having own templates. Is there a way to template this build chain - so, when I choose some meta-template - both builds will be created with present Artifact dependencies?