Can't use Color in Select/Case statement

[TomToadParticipant]

Don’t know if this is a bug, or I just misunderstand how Select/Case works.
If I compare 2 Color objects with If, everything works.

Monkey

Local currentColor:Color = Color.White If currentColor = Color.White then canvas.DrawText("Color is White",10,10)

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Local currentColor:Color = Color.White If currentColor = Color.White then canvas.DrawText("Color is White",10,10)

However, when making a comparison within a Select/Case, I get an error

Monkey

Select currentColor Case Color.White ... `C:/Users/James/Monkey2-devel/monkey2/tmp/untitled1.buildv1.1.06/windows_debug/src/untitled1_untitled1.cpp:141:28: error: no match for 'operator==' (operand types are 't_std_graphics_Color' and 't_std_graphics_Color') if(this->m_currentColor==g_std_graphics_Color_White){ ~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~ ***** Fatal mx2cc error ***** Internal mx2cc build error

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Select currentColor     Case Color.White ...   `C:/Users/James/Monkey2-devel/monkey2/tmp/untitled1.buildv1.1.06/windows_debug/src/untitled1_untitled1.cpp:141:28: error: no match for 'operator==' (operand types are 't_std_graphics_Color' and 't_std_graphics_Color')        if(this->m_currentColor==g_std_graphics_Color_White){           ~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~       ***** Fatal mx2cc error *****   Internal mx2cc build error

[nerobotParticipant]

Because r/g/b/a components of Color is Float type, and Float is not comparable type.

Try to run these examples:

Monkey

Local a:=3 Local b:=5 Local c:=-2 If a-b=c Print "equals" ' work

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Local a:=3 Local b:=5 Local c:=-2   If a-b=c Print "equals" ' work

Monkey

Local a:=0.3 Local b:=0.5 Local c:=-0.2 If a-b=c Print "equals" ' doesn't work!

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Local a:=0.3 Local b:=0.5 Local c:=-0.2   If a-b=c Print "equals" ' doesn't work!

[TomToadParticipant]

Your example has nothing to do with my problem.  [b]If currentColor = Color.White [/b] works just fine.  Succeeds when currentColor is white, fails on any other color.  The problem is not with If/Then, but with Select/Case, which won’t even compile.  Your example compiles fine, even though you don’t get the expected results.

Also, floats are comparable.  The reason why your test fails is due to the tiny imprecision caused by storing floats.  Due to that imprecision, they are rarely exactly equal. Instead, you should subtract the two and compare against a tolerance.  If c-(a-b) < .001 gives the expected results in your example.

[nerobotParticipant]

Hmm. If we add operator <=> via extension, we get different error message

Monkey

Struct Color Extension Operator <=>:Int( other:Color) Return 0 End End

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Struct Color Extension Operator <=>:Int( other:Color) Return 0 End End

Monkey

C:/proj/monkey2/tmp/untitled2.buildv1.1.06/windows_debug/include/untitled2_untitled2.h: In function 'int bbCompare(const t_default_Test&, const t_default_Test&)': C:/proj/monkey2/tmp/untitled2.buildv1.1.06/windows_debug/include/untitled2_untitled2.h:94:86: error: passing 'const t_default_Test' as 'this' argument discards qualifiers [-fpermissive] inline int bbCompare(const t_default_Test&x,const t_default_Test&y){return x.m__cmp(y);} ^ C:/proj/monkey2/tmp/untitled2.buildv1.1.06/windows_debug/include/untitled2_untitled2.h:82:9: note: in call to 'bbInt t_default_Test::m__cmp(t_default_Test)' bbInt m__cmp(t_default_Test l_other); ^

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C:/proj/monkey2/tmp/untitled2.buildv1.1.06/windows_debug/include/untitled2_untitled2.h: In function 'int bbCompare(const t_default_Test&, const t_default_Test&)':   C:/proj/monkey2/tmp/untitled2.buildv1.1.06/windows_debug/include/untitled2_untitled2.h:94:86: error: passing 'const t_default_Test' as 'this' argument discards qualifiers [-fpermissive]   inline int bbCompare(const t_default_Test&x,const t_default_Test&y){return x.m__cmp(y);}                                                                                         ^   C:/proj/monkey2/tmp/untitled2.buildv1.1.06/windows_debug/include/untitled2_untitled2.h:82:9: note:   in call to 'bbInt t_default_Test::m__cmp(t_default_Test)'      bbInt m__cmp(t_default_Test l_other);            ^

Probably, something wrong in generated c++ code.

Other operators <> ,< , > , = don’t solve error.

[nerobotParticipant]

And the same problem have a place if we create other struct like color with comparison operators.

[TomToadParticipant]

I see the problem now.  When the std.graphics.color module is compiled, an overloaded bbCompare() function is created.  In this function, the fields are compared 1×1 and result is returned.  This is what the If/Else/End statement is using to compare the two parameters.  If I overload the = operator, a function called m_eq() is created and this is used instead of bbCompare.

Monkey2

Monkey

If currentColor = Color.White Print "Current color is white" Else Print "Current color is not white" End If

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If currentColor = Color.White Print "Current color is white" Else Print "Current color is not white" End If

Compiles to C++

C++

if((bbCompare(l_currentColor,g_std_graphics_Color_White)==0)){ bb_print(bbString(L"Current color is white",22)); }else{ bb_print(bbString(L"Current color is not white",26)); }

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if((bbCompare(l_currentColor,g_std_graphics_Color_White)==0)){     bb_print(bbString(L"Current color is white",22));   }else{     bb_print(bbString(L"Current color is not white",26));   }

Now the Select/Case statement is different.  Instead of using bbCompare(), it is using C++’s built in == operator.  Since Monkey2 has no way to overload C++’s == operator, it creates the error.

monkey2

Monkey

Select currentColor Case Color.White Print "Select/Case Color is white" Case Color.Red Print "Select/Case Color is Red" Default Print "Select/Case Color is neither red nor white" End select

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Select currentColor Case Color.White Print "Select/Case Color is white" Case Color.Red Print "Select/Case Color is Red" Default Print "Select/Case Color is neither red nor white" End select

Compiles to C++

C++

if(l_currentColor==g_std_graphics_Color_White){ bb_print(bbString(L"Select/Case Color is white",26)); }else if(l_currentColor==g_std_graphics_Color_Red){ bb_print(bbString(L"Select/Case Color is Red",24)); }else{ bb_print(bbString(L"Select/Case Color is neither red nor white",42)); }

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if(l_currentColor==g_std_graphics_Color_White){     bb_print(bbString(L"Select/Case Color is white",26));   }else if(l_currentColor==g_std_graphics_Color_Red){     bb_print(bbString(L"Select/Case Color is Red",24));   }else{     bb_print(bbString(L"Select/Case Color is neither red nor white",42));   }

So the solution would be either 1) Have Select/Case use bbCompare instead of == or 2) be able to override == at the C++ level.

[Mark SiblyKeymaster]

It’s definitely a compiler bug, would you mind posting an issue at github?

[Author]

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