About the Evaluate/Modify function
lazarus / 10-Designer

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yinhuajian · 2025-05-30 03:36

During Delphi debugging, you can press [Ctrl + F7] to bring up the
[Evaluate/Modify] window.
In this window, I can assign a [New Value] to a variable. This [New
Value] can be either a concrete value (like 5) or a value returned
from a function (e.g., GetVal()). Naturally, this means you can also
execute a [Procedure] in the [New Value] window, such as
SqlToTxtFile().

When debugging, I sometimes need to output complex SQL queries to a
.txt file and open it, which proves extremely convenient for debugging
purposes.

I've noticed Lazarus has a similar feature, but with one key
difference: in its [New Value] field, you can only assign concrete
values to variables (like 5) — you cannot call functions or
procedures. Are there any alternative approaches to achieve this in
Lazarus? Thank you.

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Martin_fr · 2025-05-30 07:49

You can create a feature request for this.

So far simply no one has thought of it, or ever asked for it.

It will be a bit of time before it gets considered, because I am quite
busy with other stuff right now.


You can obviously watch/evaluate other variables first, and then copy
and assign the result. => So that works for simple values only.

You can also call functions, if you need to see the result of a
function. To do that
- FpDebug only / Windows or Linux only / x86 or i386 only.
- Enable function calls globally in Tools > Options > debugger
- Enable for the Watch or in inspect or in eval window (only for the
viewed value, not for the assignment).