Re: A way to mixin during runtime?
On Friday, 27 August 2021 at 06:52:10 UTC, Kirill wrote: Is there a way to do mixin or similar during runtime? I'm trying to read a csv file and extract data types. Any ideas on how this should be approached in D are greatly appreciated. mixin at runtime not possible. Source code compilation and runing in runtime not possible. But! But you can impement this! Steps: 1. Need D compiller 2. In runtime you can compile mixin to dynamic library (.so or .dll) using external command: `dmd ...` 3. Load dynamic library using `dlopen()` `dlsym()` `dlclose()`. (on Windows: LoadLibrary(), GetProcAdres(), FreLibrary()) 4. Call mixin functions, variables 5. Done! Packages bindbc-*, derelict-* uses dynamic loading. You can use both as examples.
Re: A way to mixin during runtime?
On 8/27/21 6:34 AM, Kirill wrote:
On Friday, 27 August 2021 at 09:51:46 UTC, Mathias LANG wrote:
On Friday, 27 August 2021 at 06:52:10 UTC, Kirill wrote:
Is there a way to do mixin or similar during runtime?
I'm trying to read a csv file and extract data types. Any ideas on
how this should be approached in D are greatly appreciated.
You cannot mixin at runtime. However, it is fairly easy to map a
finite and CT-know set of argument to runtime arguments via `static
foreach`.
Could you give us example of the content of your CSV file and what you
are trying to do ?
Each csv file will be different.
For example:
```
name;surname;age;grade
Alex;Wong;18;87
John;Doe;19;65
Alice;Doe;18;73
etc...
```
I'd like to extract the data types automatically. For instance, if using
tuples:
```
Tuple!(string, string, int, int) ...
```
instead I'd like to have:
```
auto mytuple = read_csv(path); // returns Tuple!(string, string, int,
int)[]
```
So you can't build "new types" at runtime that are usable after your
code is compiled. But there are options:
1. You can parse the CSV at compile-time using `import("types.csv");`
and then processing the resulting string using CTFE (not sure if std.csv
does this, but I'd expect it to). Then you can use the resulting thing
to generate string mixins that can generate types. This has the drawback
that you need to recompile when your csv input changes.
2. You can create a dynamic type that deals with the CSV data. It looks
from your CSV data you are inferring the "type" from the data itself,
which is complex in itself. In this case, you'd use it kind of like a
JSON object, where you index the fields by name instead of using
`obj.name`, and you'd have to extract the type dynamically from the type
inference you'd have to write. This is pretty much what std.csv does,
though you can dress it up a bit more.
Without the CSV telling you types, it's hard to make something "easy". I
have written code that extracts from JSON data and database data
serializable struct types, and builds a D file, but it's never
clean-cut, and sometimes you have to hand-edit that stuff. This is about
as "easy" as it gets, just have the computer do most of the heavy
lifting, and then massage it into something usable.
-Steve
Re: A way to mixin during runtime?
On Friday, 27 August 2021 at 10:34:27 UTC, Kirill wrote: Each csv file will be different. For example: ``` name;surname;age;grade Alex;Wong;18;87 John;Doe;19;65 Alice;Doe;18;73 etc... ``` I'd like to extract the data types automatically. For instance, if using tuples: ``` Tuple!(string, string, int, int) ... ``` instead I'd like to have: ``` auto mytuple = read_csv(path); // returns Tuple!(string, string, int, int)[] ``` mytuple needs to have a type that's known at compile-time, so this isn't possible. In the types are only dynamically known, then you have to deal in dynamic types. One way could be to have a read_csv that returns an array of https://dlang.org/phobos/std_variant.html
Re: A way to mixin during runtime?
On Friday, 27 August 2021 at 09:51:46 UTC, Mathias LANG wrote: On Friday, 27 August 2021 at 06:52:10 UTC, Kirill wrote: Is there a way to do mixin or similar during runtime? I'm trying to read a csv file and extract data types. Any ideas on how this should be approached in D are greatly appreciated. You cannot mixin at runtime. However, it is fairly easy to map a finite and CT-know set of argument to runtime arguments via `static foreach`. Could you give us example of the content of your CSV file and what you are trying to do ? Each csv file will be different. For example: ``` name;surname;age;grade Alex;Wong;18;87 John;Doe;19;65 Alice;Doe;18;73 etc... ``` I'd like to extract the data types automatically. For instance, if using tuples: ``` Tuple!(string, string, int, int) ... ``` instead I'd like to have: ``` auto mytuple = read_csv(path); // returns Tuple!(string, string, int, int)[] ```
Re: A way to mixin during runtime?
On Friday, 27 August 2021 at 06:52:10 UTC, Kirill wrote: Is there a way to do mixin or similar during runtime? I'm trying to read a csv file and extract data types. Any ideas on how this should be approached in D are greatly appreciated. You cannot mixin at runtime. However, it is fairly easy to map a finite and CT-know set of argument to runtime arguments via `static foreach`. Could you give us example of the content of your CSV file and what you are trying to do ?
Re: A way to mixin during runtime?
On Friday, 27 August 2021 at 06:52:10 UTC, Kirill wrote: Is there a way to do mixin or similar during runtime? I'm trying to read a csv file and extract data types. Any ideas on how this should be approached in D are greatly appreciated. remember D is a statically compiled language, `mixin` is for generating code, so, it won't work except you have a runtime code parser. you may need a scripting language embedded in your D app to achieve this. thx.
A way to mixin during runtime?
Is there a way to do mixin or similar during runtime? I'm trying to read a csv file and extract data types. Any ideas on how this should be approached in D are greatly appreciated.
