RemoveIf example

This topic contains 7 replies, has 3 voices, and was last updated by degac 1 year, 5 months ago.

Viewing 8 posts - 1 through 8 (of 8 total)

Author

Posts

November 13, 2017 at 9:14 pm #11683

Participant

Hi
I’m trying to understand how to use the method RemoveIf… but without results…

Namespace myapp

#Import "<std>"

Using std.collections
Using std.stringio


Function Main()

	Local st:=New Stack<Int>
	
	st.Add(10)
	st.Add(20)
	st.Add(123)
	
	st.RemoveIf(CheckIt(40)) 'I would like to remove all the items with 'value' greater of 40 (for example)
		
End

Function CheckIt:Bool()

End

Namespace myapp

#Import "<std>"

Using std.collections

Using std.stringio

Function Main()

Local st:=New Stack<Int>

st.Add(10)

st.Add(20)

st.Add(123)

st.RemoveIf(CheckIt(40)) 'I would like to remove all the items with 'value' greater of 40 (for example)

End

Function CheckIt:Bool()

End

November 14, 2017 at 1:51 am #11689

Mark Sibly

Keymaster

The parameter for RemoveIf should be a function:

Namespace myapp
 
#Import "<std>"
 
Using std.collections
Using std.stringio
  
Function Main()
 
	Local st:=New Stack<Int>
	
	st.Add(10)
	st.Add(20)
	st.Add(123)
	
	st.RemoveIf( CheckIt ) 'I would like to remove all the items with 'value' greater of 40 (for example)

	For Local i:=Eachin st
		Print i
	Next		
End
 
Function CheckIt:Bool( value:Int )
	
	Return value>40
End

Namespace myapp

#Import "<std>"

Using std.collections

Using std.stringio

Function Main()

Local st:=New Stack<Int>

st.Add(10)

st.Add(20)

st.Add(123)

st.RemoveIf( CheckIt ) 'I would like to remove all the items with 'value' greater of 40 (for example)

For Local i:=Eachin st

Print i

End

Function CheckIt:Bool( value:Int )

Return value>40

End

…you can use a lambda to write the function ‘inline’ too:

	st.RemoveIf( Lambda:Bool( value:Int )
		Return value>40
	End )

st.RemoveIf( Lambda:Bool( value:Int )

Return value>40

End )

November 14, 2017 at 12:11 pm #11698

degac

Participant

Ahhh… many thanks!
So I can’t pass a value to check (ie: RemoveIf(Check(40)), it must be already defined in the function!
I misunderstood the meaning/syntax of it!
I should define a global to change the behavior, same in case of Lambda()

November 15, 2017 at 2:48 am #11705

nerobot

Participant

Also, you can write & use extension methods, look at example:

Namespace myapp

#Import "<std>"

Using std..

Function Main()

	Local st:=New Stack<Int>
	st.AddAll( New Int[](-2,0,10,54,3,-7) )
	Print "source values:"
	For Local i:=Eachin st
		Print i
	Next
	st.RemoveIfLess( 0 )
	Print "filtered values 1:"
	For Local i:=Eachin st
		Print i
	Next
	st.RemoveIfGreater( 50 )
	Print "filtered values 2:"
	For Local i:=Eachin st
		Print i
	Next
End


Class Stack<T> Extension
	
	Method RemoveIfGreater( valueToCompare:T )
	
		Self.RemoveIf( Lambda:Bool( value:T )
			Return value>valueToCompare
		End )
	End
	
	Method RemoveIfLess( valueToCompare:T )
	
		Self.RemoveIf( Lambda:Bool( value:T )
			Return value<valueToCompare
		End )
	End
	
	Method RemoveIfEquals( valueToCompare:T )
	
		Self.RemoveIf( Lambda:Bool( value:T )
			Return value=valueToCompare
		End )
	End
	
End

Namespace myapp

#Import "<std>"

Using std..

Function Main()

Local st:=New Stack<Int>

st.AddAll( New Int[](-2,0,10,54,3,-7) )

Print "source values:"

For Local i:=Eachin st

Print i

st.RemoveIfLess( 0 )

Print "filtered values 1:"

For Local i:=Eachin st

Print i

st.RemoveIfGreater( 50 )

Print "filtered values 2:"

For Local i:=Eachin st

Print i

End

Class Stack<T> Extension

Method RemoveIfGreater( valueToCompare:T )

Self.RemoveIf( Lambda:Bool( value:T )

Return value>valueToCompare

End )

End

Method RemoveIfLess( valueToCompare:T )

Self.RemoveIf( Lambda:Bool( value:T )

Return value<valueToCompare

End )

End

Method RemoveIfEquals( valueToCompare:T )

Self.RemoveIf( Lambda:Bool( value:T )

Return value=valueToCompare

End )

End

November 15, 2017 at 12:25 pm #11713

degac

Participant

o.O wow! this is really… ingenious!
I would never have though to Extension to resolve the problem! I need to change paradigm… Monkey2 seems have so many interesting way to solve things!

Thank you very much!

edit:

this thing about Stack (or list) and RemoveIf() method & solutions *should* be added to some guide/tutorial/help… It’s a simple thing that shows many features of Monkey2!

November 15, 2017 at 11:50 pm #11729

Mark Sibly

Keymaster

…just wanted to see if this would work really (it does!), getting a bit ‘c++’-ish for my liking though…

#Import "<std>"

Using std..

Function LessThan<T>:Bool( val:T )( cmp:T )
	
	Return Lambda:Bool( val:T )
	
		Return val<cmp
	End

End

Function Main()
	
	Local stack:=New IntStack
	
	For Local i:=0 Until 100

		stack.Add( Rnd( 100 ) )
	End
	
	stack.RemoveIf( LessThan( 50 ) )
	
	For Local val:=Eachin stack
		
		Print val
	Next
	
End

#Import "<std>"

Using std..

Function LessThan<T>:Bool( val:T )( cmp:T )

Return Lambda:Bool( val:T )

Return val<cmp

End

Function Main()

Local stack:=New IntStack

For Local i:=0 Until 100

stack.Add( Rnd( 100 ) )

End

stack.RemoveIf( LessThan( 50 ) )

For Local val:=Eachin stack

Print val

End

November 17, 2017 at 4:34 am #11762

nerobot

Participant

Function LessThan<T>:Bool( val:T )( cmp:T )

Wow, two pairs of brackets, it’s an undocumented cheat!
And it works. My life will never be the same…

November 17, 2017 at 6:24 pm #11780

degac

Participant

Monkey2 is a … ‘monster’ even for its creator

Author

Posts

Viewing 8 posts - 1 through 8 (of 8 total)

You must be logged in to reply to this topic.

RemoveIf example

Archives

Recent Replies

What is this?