Re: [Bug-apl] Reading and updating the content of a variable

[Juergen Sauermann]

Hi,

say the name of a user-defined variable is contained in some UCS_string:

UCS_string varname;

Step 1: ----------------------------------------------

You first get a Symbol *:

Symbol * var_symbol = Workspace::lookup_existing_symbol(varname);

The pointer is 0 if varname does not exist. If the variable is 
system-defined, then
it has a direct access method Workspace::get_v_quad_IO() for ⎕IO that 
returns the Symbol &
of the symbol and it is guaranteed to exist.

Symbol * quad_IO =_symbol &Workspace::get_v_quad_IO();

Step 2: ----------------------------------------------

Once you have the Symbol * or &, you can assign or reference it:

Value_P new_value;
...
var_symbol->assign(new_value, LOC);

Value_P value = var_symbol->get_apl_value();
...

In the second example, DO NOT optimize the creation of Value_P value 
away, because
this may break the shared pointer based memory allocation.

/// Jürgen


On 01/07/2014 07:12 AM, Elias Mårtenson wrote:
> I'm currently looking to adding the ability to read and update 
> variables via the backend connection. This will eventually be used to 
> display arrays in separate buffers (and perhaps a spreadsheet-like 
> editor for such values).
>
> I would like to advice on how to best do this without using too much 
> low-level stuff in the interpreter. I was thinking that perhaps I 
> could leverage some of the code in the workspace save and load functions?
>
> All I really need is to be able to get and update a limited set of 
> data. I.e. Scalars, and 1 and 2-dimensional arrays where the elements 
> are either scalars or strings.
>
> I'm currently looking at doing this "manually", but before I get too 
> far I wanted to know if you had any opinions.
>
> Regards,
> Elias