How can I create a constant in the Snap! programming language?
I use a custom reporter block that returns a single value.
Change to the Variables palette
Select "Make a block"
Name your constant, select "Reporter", and click OK
Enter the constant value in the report block and click OK
Insert the new block wherever you would like to use the constant
It would be useful to know the purpose of the constant.
If you are comfortable with creating a constant global variable, it may be slightly easier than the above method:
Choose the "Variables" palette.
Choose "Make a Variable."
Directly below this variable, select "Set _ to 0" and set this constant variable to the desired value. You can use this variable wherever (same as above).
Related
I am trying to assign the value of this stucture path to a fieldsymbol, but this path does not work because it has a table in it's path.
But with in the debugger this value of this path is shown correctly.
Is there a way to dynamically assign a component of a table line to a fieldsymbol, by passing one path?
If not then I will just read the table line and then use the path to get the wanted value.
ls_struct (Struct)
- SUPPLYCHAINTRADETRANSACTION (Struct)
- INCL_SUPP_CHAIN_ITEM (Table)
- ASSOCIATEDDOCUMENTLINEDOCUMENT (Element)
i_component_path = |IG_DDIC-SUPPLYCHAINTRADETRANSACTION-INCL_SUPP_CHAIN_ITEM[1]-ASSOCIATEDDOCUMENTLINEDOCUMENT|.
ASSIGN (i_component_path) TO FIELD-SYMBOL(<lg_value>).
IF <lg_value> IS NOT ASSIGNED.
return.
ENDIF.
<lg_value> won't be assigned
Solution by Sandra Rossi
The debugger has its own syntax and own logic, it doesn't apply the ASSIGN algorithm at all. With ABAP source code, you have to use ASSIGN twice, the first one to reach the internal table, then you select the first line, and the second one to reach the component of the line.
The debugger works completely differently, the debugger code works only in debug mode, you can't call the code from the debugger (i.e. if you call it, the kernel code used by the debugger will fail). No, there's no "abappath". There are the XSL transformation objects (xpath), but it's slow for what you ask.
Thank you very much
This seems to be a rather unexpected limitation of the ASSIGN statement. Probably worth a ticket to SAP's ABAP language group to clarify whether it's even a bug.
While this works:
ASSIGN data-some_table[ 1 ]-some_field TO FIELD-SYMBOL(<lv_source>).
the same expressed as a string doesn't:
ASSIGN (`data-some_table[ 1 ]-some_field`) TO FIELD-SYMBOL(<lv_source>).
Alternative 1 for (name) of the ABAP keyword documentation for the ASSIGN statement says that "[t]he name in name is structured in the same way as if specified directly".
However, this declaration is immediately followed by "the content of name must be the name of a data object which may contain offsets and lengths, structure component selectors, and component selectors for assigning structured data objects and attributes in classes or objects", a list that does not include the table expressions we would need here.
A program variable is an abstraction of a computer memory cell or collection
of cells. Programmers often think of variable names as names for memory locations, but there is much more to a variable than just a name.
In this case, what is an anonymous variable?
What does the below statement mean?
Variables without names are called anonymous variables.
Can you provide language specific examples for the same?
In C++, reference variable to const can be initialized by constant.
In this point, temporary variable is created in memory to grab the constant.
const int &ref = 3;
like this. so we can call this temporary variable to "anonymous variable".
Variables are where you store you values. 'Variable Name' is the usually the easiest (and more human-like) way to locate your value.For example, if I am a variable, you can get my value by calling my name, and the combination of my value and my name is called 'variable'.
However, not all variables need a name.Sometimes you just use them once and don't need them anymore; and in that case, a name is unnecessary.
The example given by #BAE HA RAM is a telling one,in which case you don't need a name for the value but ref to it by a pointer(But still got a name for that pointer)..
There are also many other anonymous things, anonymous type, anonymous function and so on. Most of them are created to avoid too many meaningless names for the things that you only need to run once.
I'd like to know which language you are using, so more specific example can be given...
Is it possible, in ABAP, to evaluate string templates dynamically?
Normally, you will have some string template in code that will be checked by the compiler. (The variables in the curly brackets are checked by the compiler at compile time).
However, is it possible to have a string evaluated at runtime?
So, instead of:
data(val) = |System ID: { sy-sysid }|.
I would like the string to be interpolated to come from elsewhere, for example:
parameter: p_file type string lower case default '/mnt/{ sy-sysid }/file.txt'.
In this case, I would like to have the value of p_file to be evaluated at runtime to substitute the variable (sy-sysid) with the runtime value.
You could, of course, program your own substitution by finding all occurrences of variables with curly brackets with a regex expression, then evaluate the variable values with ASSIGN and substitute them back into the string, but I am looking for a built-in way to do this.
Sorry, this is maybe a stupid example, but hopefully you understand what I mean. (If not, please let me know in the comments and I will try and clarify).
The problem in your snippet is not with string template but with PARAMETER behavior. It does not allow dynamics in DEFAULT clause.
To achieve what you want you should use INITIALIZATION and set path value in runtime:
parameter: p_file type string lower case.
INITIALIZATION.
p_file = | /mnt/{ sy-sysid }/file.txt |.
Unfortunately, the example you gave, does not make any sense to me. ABAP String templates are evaluated at run-time and type-checked at compile-time.
In your example, it is always the run-time value of SY-SYSID that will be written to the variable.
I guess what you want to do is circumvent compile-time checks for expressions inside a string template.
Please try to give us your actual use case, so maybe we find an even better solution to your problem.
However, here is what I think could help you:
Personally, I do not recommend to write code like the one below, because it is extremely error-prone likely to mislead other programmers and because there is very likely a better solution.
Given that you know the name of a variable at run-time, try this:
".. say LV_VARNAME is a charlike variable that contains a
" variable name at runtime.
"NOTE that the variable LV_VARNAME must be visible in the scope of the
"following code.
FIELD-SYMBOLS: <my_var> TYPE any.
ASSIGN (lv_varname) TO <my_var>.
DATA(lv_str) = |The value is { <my_var> }|.
In Elisp I have introduced for a special custom mode a variable like:
(defvar leo-special-var "")
(make-variable-buffer-local 'leo-special-var)
Now I set this variable in files I with the lines (in the file to edit):
# Local Variables:
# leo-special-var: "-d http://www.google.com.au"
# End:
And I want to consider this variable as "safe for all its values. That's why safe-local-variable-values doesn't help. Instead I tried (in the lisp code):
# setting the symbol property of the variable
(put 'leo-special-var 'safe-local-variable 'booleanp)
but without success. Do I do something wrong when setting the symbol property? Or is there another way?
You want to use
(put 'leo-special-var 'safe-local-variable #'stringp)
to say that it is safe as long as it's a string.
If you really want to state that it is safe for all values then use this:
(put 'leo-special-var 'safe-local-variable (lambda (_) t))
The function to test safety here returns non-nil for any value.
(But I'd think that you probably do not want to state that a variable is safe for any value.)
It's in the manual: (elisp) File Local Variables
You can specify safe values for a variable with a
`safe-local-variable' property. The property has to be a function of
one argument; any value is safe if the function returns non-`nil' given
that value. Many commonly-encountered file variables have
`safe-local-variable' properties; these include `fill-column',
`fill-prefix', and `indent-tabs-mode'. For boolean-valued variables
that are safe, use `booleanp' as the property value. Lambda
expressions should be quoted so that `describe-variable' can display
the predicate.
When defining a user option using `defcustom', you can set its
`safe-local-variable' property by adding the arguments `:safe FUNCTION'
to `defcustom' (*note Variable Definitions::).
In VBA, I want to use a name for a local variable that I'd also like to use for a function name. The problem I'd that the function name formatting always changes to the local variable formatting.
Any way to prevent that?
I highly recommend not using the same name for disambiguation purposes. Also, if VBA is not case sensitive, it may not know whether you are referring to the function or the variable and thus give a runtime error (I don't think it is compiled per se, but it goes to a proprietary p-code intermediate.)
Often when you'd like the names to be similar, it can be useful to prepend an underscore to one, such as a local variable. Thus I recommend you name the function FunctionName and the variable _FunctionName if you want to go that route.
If you want to try having the same name for each, you will likely need to edit the code outside of the IDE that is reformatting your code. In an editor that doesn't try to auto-format, you may be able to force it. Then whether it compiles or not is the question.
In Visual Basic, each function already has a variable named after the function. Assigning a value to this variable is the only way to set a return value for this function.
Therefore, declaring yet another variable of the same name creates ambiguity. You cannot do so. It results in the Duplicate declaration in current scope error.
And if by "local" variable you meant a module-level variable, then you cannot do it either: Ambiguous name detected: %s.
And if you are asking about a situation when a function and a variable of the same name belong to different scopes, then VBA will use the case of the line that was edited last. So if you declare a function and then declare a variable in another module, the function name will change case. But if you then return to the function, change its casing back and press Enter, the variable, in its turn, will change its casing to match the function name.