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##### Activity
John Moreno
@jrmoreno1
@AdamSpeight2008: just the obvious of checking against min/max manually, be a bit complicated but doable
Are allowing arbitrary step size?
Paul M Cohen
@paul1956
I don't understand purpose of stepping
me neither
what is the use case where you are doing a range check.. and you have some concept of a step?
John Moreno
@jrmoreno1
Find the difference between min/max and then compare that to step and MaxValue-value
when is that useful?
when would i use IsBewteen?
John Moreno
@jrmoreno1
@CyrusNajmabadi : don’t know his use case, but it could be useful when examining a for loop with a step
Although I have never had a for/step with values anywhere near the limits….
i'm asking what hte use case is because i don't understand it :)
i genuinely can't even figure out what that code really does :)
Paul M Cohen
@paul1956
I think it is for a "For i as byte = Byte.Min to Byte.Max Step anything" and I don't believe it ever worked correctly in VB when step is used especially when it is negative. But I can't point out what is broken, there was a bug report when I first started looking a Roslyn. This goes back a very long time and I have never used it.
i understand stepping in teh context of a for loop
it's how the value is incremented/decremented at the end of each pass.
what i don't undertand is hte IsBewteen method and what it does
Paul M Cohen
@paul1956
I think it was proposed to replace the For loop to handle the edge cases. While i.Inbetween(Byte.Min, Byte.Max, Step:=2) But maybe Adam had something else in mind.

I want to fairly efficiently to check if a value, is within two bounds but that range isn't continuous but has a regular stepping.
start := 0, finish := 10, stepping:= 2' Ifvalue:=2then return true. Ifvalue=7 return false.
The following works, assuming we if pass in arguments that satisfies the for loop conditions.

Function IsBetween(value as Integer, start As Integer, finish As Integer, stepping As Integer ) As Boolean
For index = start To finish Step stepping
If index = value Then Return True
Next
Return False
End Function

But it is rather inefficient, since we could check if a value is within some bounds simply using Math.Min(start, finish) <= value and value<=Math.Max(start, finish). But this doesn't take into account a stepping. My question is, "Is there an efficient way to do that?"

why do you need the for loop?
ignoring negatives for now, isn't this just seeing if the distance from start to your value is a integer multiple of your step?
so like... (value - start) % step == 0`?
you're basically asking: could i step an exact number of times from start and that added to start would equal value.
@VBAndCs
I am adding new language features to small basic, such as indexing string x[0]. This one was easy as i am working on the sb vetsion that has no runtime. It just generates il code which calls the methods of the primitive class to do every thing. So i just modified the primative class to ondex the string with some more fantastic features when calling the indexer setter, like padding spaces when the index is negative or greater that the string length, and allowing setting a string with any lingth i
I am now trying to add array initializer
I did the parsing part smoothly and it allows nested {}
The code compiles fine, but of couse i don't know how to emit il code for that!
I can't use a method in the premative class because sb will not accept param array
Ineed to do it at the il level
A work arroun is to lower the initializer to many arrat cells assignment
@VBAndCs
But this will mess with the line numbers in err messages
So, il it is
Any idea where to begin reading?
It can seem daunting at first.
But it's actually super simple
And then you realize there's no magic here. Just a lot of basic opcodes that do sensible things
Cory Smith
@DualBrain
@VBAndCs
I already solved the issue and aray initializerscworks now in sb (will puplish it in minutes) :)
I totakly avoided il. I tried to deliver to the il generator only the syntax it understands
So, i loweted the code in the emit phase to avoid altering the source code text
@VBAndCs
To do that, i cteated the lowed code as a separit code, parsed and analyzed it, then added the resuling info to the original compilation,. Finally i used the same generator scope to emit il for the new parse tree of the lowered code
And since i am already in the middle of ghe emmit phase, the il for the lowered code is its right pos, and of course i don't emit anything for the original array initializer
Il spy is a grate help, since i used it to figure out what i did wrong in emmiting il.