Is it possible to call a function that was created from string literal? For example
${object}.staticPartOfFunctionName${dynamicPartOfFunctionName}()
doesn't return correct value, but instead just prints the object and the function name.
$object.staticFunctionName()
prints correctly, and
$object.staticPartOfFunctionName${dynamicPartOfFunctionName}()
gives warning "Encountered ")"
You don't have to use introspection:
#evaluate("\$object.staticPartOfFunctionName${dynamicPartOfFunctionName}()")
Well, I found one solution myself from Java side:
$object.getClass().getMethod("staticPartOfFunctionName$dynamicPartOfFunctionName").invoke($object))
I don't know if it's any good, so if someone knows how to do it velocity way, lemme know.
Related
Google turns up nothing on this error: Combination of indirect name lookup and call not supported
My code:
use Vimwiki::File::TextProcessingClasses;
unit class Vimwiki::File::ContentStr;
has Str $.content;
method process($class) {
$!content = Vimwiki::File::TextProcessingClasses::($class).process($!content);
}
The compiler is not happy with this and complains with aforesaid error. If I hard-code in in the $class name, everything works.
Anyway around this?
OK, solution is to precede the package name with ::, like so:
$!content = ::Vimwiki::File::TextProcessingClasses::($class).process($!content);
Documentation is here: https://docs.raku.org/language/packages#Looking_up_names
Though I don't know precisely why what I was doing originally behaves differently.
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> }|.
I would like to make a function which would allow me to pass a string in the argument - what's the best way to do this?
eg..
Moles("Ca(OH)2")
Any help would be extremely gratefully received.
I ended up putting this in by parsing strings as variables. So for DDMathParser:
someFunction("Hello")
... is equivalent to:
someFunction($Hello)
However, this means you can have variables now with more complex stuff:
someFunction("Hello world")
Moles("Ca(OH)2")
... etc
As you seen in this picture below, for some reason my DirectCast wont except ANYTHING for the second argument. It says it requires a type, but, it won't take any object at all!
Thanks for any help! I'm using VB.net so all .net answers are acceptable :)
EDIT
Ok, so apparently I'm not giving it the right kind of type. Could somebody please clarify this? Assuming the type it needs to cast to is gridElement, what should I replace objType with?
DirectCast requires an object prototype (i.e. just giving it the intended class name) rather than a System.Type descriptor object. To cast an object using a System.Type, you will want to utilize CTypeDynamic():
Return CTypeDynamic(createElementByIdAndLayer.MemberwiseClone(), objType)
The error is essentially telling you a class with the type name "objType" does not exist.
Its expecting a "Type", not a "Type Object".
What is the return value of the function?
What is the difference between using ToString and ToString() in VB.NET?
Nothing. VB.NET allows you exclude the parentheses on any method that doesn't take in an argument.
The existing answer is wholly correct but does not cover when ToString is used as a Method. This is essentially incorrect coding but it is possible
Dim sbrBuilder as New StringBuilder
...
sbrBuilder.ToString()
return sbrBuilder.ToString
The first ToString (which does nothing) does not produce an error but the brackets are forced on by the IDE. The second ToString does not require brackets (optional - as explained already in the Answer) as it is used to collect the value of ToString.
Hopefully this will help anyone who is wondering why the IDE keeps adding brackets on ToString - then you will realise that you forgot to assign it to anything like I did