nimforum mirror - some macro questions

adrianv (orginal) [2012-10-24T11:41:19+02:00] view original

hi,

macros are pretty cool !

there are some things I didn't find out until now:

if I process a statement with a macro and this resulting statement has an error, the compiler gives me the location where in the macro this error was produced (which is good for debugging the macro), but not the location in the source code from which I have called the macro. Is there a way to get both - like in a template (instantiated from...)

is there a way to access some "global" information from inside a macro. Lets say I have generated some type with a macro call and later on in a second macro call I want to access some of the information of what I have generated before.

Or another thing I am thinking of: In a first call to a macro I pass the name of a database. This macro generates some structural information from the database structure. Later on I pass a query inside a string to a macro and this macro checks if the query is sane and produces a compile time type checked query. Now when I start the app, the actual database structure is checked against the structure at compile time - if they are compatible the app runs, otherwise it fails with some message (or updates the database to an actual structure).

cheers, Adrian.

Araq (orginal) [2012-10-25T13:02:43+02:00] view original

The compiler should produce an "instantiation from here" message for macro invokations. If it doesn't, that's a bug.

You can use var x {.compileTime.}: TTable[x, y] to store and load global information.

An ORM that parses an SQL schema at compile time and generates a typesafe Nimrod API for it is planned but apart from the SQL parser in the stdlib no code exists for that yet; if you feel like it, you can do it and I'll gladly add it to the distribution.

adrianv (orginal) [2012-10-25T18:05:24+02:00] view original

The compiler should produce an "instantiation from here" message for macro invokations

I think it is a bug then. But I will check before I create an issue.

use var x {.compileTime.}: TTable[x, y]

oh stupid me, its obvious - I tried {.global.} ;-)

An ORM that parses an SQL

I am not thinking of pure SQL at the moment, because we have our own database server (object relational) with a slightly different query language. This database server is currently written in Delphi, but I started already to port it to nimrod and this version will be open source (but I am unsure about which license it will be at the end - most likely GPL + Commercial).

Araq (orginal) [2012-10-25T22:49:32+02:00] view original

This database server is currently written in Delphi, but I started already to port it to nimrod and this version will be open source

Excellent news. There is nothing better to promote a language than production software written in it. :D

adrianv (orginal) [2012-10-26T20:51:33+02:00] view original

I believe that nimrod is worth any promotion possible !

it is perfect for implementing algorithms (and you get generic for free)

it doesn't force you to any particular programming style

it forces you to write memory-sane programs

its template system allows you to get rid of all that boilerplate code

its macro system allows you to do really cool things - I feel like programming in Forth, but human readable

many things to add ......

and it's fast.

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97 :: some macro questions