Execute statement

[DeiRex75]

Similar to the set statement i was in need of a execute statement.

The execute statement executes a given expression but doesn't render it.
This helps to call functions that just want to be executed.
For example, adding a debug function that dumps the object but doesn't change the result.

I would love to have this or something similar added.

{% execute a_dump_function(data) -%} Something was dumped.

Would just result in "Something was dumped."

This use case is just an example. Not a good one to be honest.
The issue is that currently no option is available to just call a function without rendering something.
Using an expression and returning "" doesn't allow for whitespace control.

[pantor]

Thanks for your PR!

I think I would integrate your execution statement within the callback approach. I've added a void callback to the master branch, maybe you can have a look at this. An example for that would be:

// You can also add a callback without return variable, e.g. for debugging:
env.add_void_callback("log", 1, [greet](Arguments args) {
	std::cout << "logging: " << args[0] << std::endl;
});
env.render("{{ log(neighbour) }}", data); // Prints nothing to result, only to cout...

[DeiRex75]

Overall love your approach.
But the major part i wanted from this was the whitespace control.

I use template files.
Therefore i would have to write:

{{ log("A") }}{{ log("B") }}{{ log("C") }}Lorem Ipsum

To process the logging and write the text without additional lines.
What i would like to write is:

{{ log("A") }}
{{ log("B") }}
{{ log("C") }}
Lorem Ipsum

to result just in "Lorem Ipsum".
Whitespace control is only possible for statements.
Therefore another possibility to result not in multiple lines would be to add a statement with control at the end of each logging line.

Another idea could be to remove the newline after an expression if "-}" or "-}}" is used to close it.
This would have to be explicit and not be affected by trim_blocks

[pantor]

Ah, I see.

I think we should follow jinja2 here and add whitespace control to variables as well. Btw, It is quite hidden in their documentation that it works for variables as well.

[DeiRex75]

Thanks for the information again.
If it is in jinja2 i would love to see this implemented as well.
I will close this for now.