On Sunday, 13 September 2020 at 10:16:46 UTC, Paul Backus wrote:
On Sunday, 13 September 2020 at 07:00:36 UTC, mw wrote:
Here it is: D wrapper for https://ta-lib.org/
https://github.com/mingwugmail/talibd
I end up using C macro to generate D functions, the single
template is this one:
https://github.com/mingwugmail/talibd/blob/master/source/talibd.h#L117
#define DECL_TA_FUNC(TA_FUNC, FUNC_INS, FUNC_OUTS,
expected_lookback) __NL__\
The most straightforward way to do this in D is with a mixin
template. Something like:
mixin template DECL_TA_FUNC(string TA_FUNC, FUNC_INS,
FUNC_OUTS, int expected_lookback)
{
bool impl(...)
{
// ...
}
// Could also wrap the whole function in a string mixin,
// but this is easier.
mixin("alias ", TA_FUNC, " = impl;");
}
Which you would then use like this:
mixin DECL_TA_FUNC!(
"TA_MA",
Tuple!(int, "MA_optInTimePeriod", TA_MAType, "opInMAType"),
Tuple!(double[], "outMA"),
MA_optInTimePeriod - 1
);
Thanks, I will do the exercise some other day.
But, I'd reflect on my experience so far on compile-time
meta-programming in D as a novice user, the big problems are:
-- in D, there are too many choices, with no clear guideline
which one is *THE* one to use for a particular purpose: language
or library mechanisms? mixin? template? AliasSeq / aliasSeqOf?
Tuple? (non-)?-eponymous version of ...?; and even for a
particular option, e.g. Tuple!(int, "MA_optInTimePeriod",
TA_MAType, "opInMAType"), there are choices to use either token
(int) or string ("MA_optInTimePeriod"). And user does not have a
strong guide on which choice is *THE* way to proceed. Each
mechanism seems to have / fit a particular purpose, but when you
start to use it, you'll probably find there are new problems
come-in later, and you want to revisit the choice you made
earlier on.
By contrast, in C: there is only *ONE* mechanism, i.e. macro,
that's it.
-- in D, there is no easy way to convert between token <==>
string. Given a token, does token.stringof always work to paste
with other strings to generate a new token? and given a string,
does mixin!"string" always work to be a valid token?
By contrast, in C: there is only *ONE* way: xxx ## yyy.
-- in D, there is no easy way to see directly the generated
source code by the compiler at compile-time, which makes the
debug difficult during development.
By contrast, in C: one can easily see the result via: cpp -P
foo.h > foo.c
As I said earlier, I'm not very experienced with C macros either,
however with some googling, I was able to work out a C macro
version to generate D code; but with all the help so far, I still
have no confidence that I can work out a solution in D to
implement this:
```
bool impl(...)
{
// ...
}
```
