Lack of block comments in VB .NET?

问题:

Just a question of interest: Does anyone know why there's no block comment capability in VB .NET? (Unless there really is - but I've never yet come across it.)

回答1:

It is a side-effect of the Visual Basic syntax, a new-line terminates a statement. That makes a multi-line comment pretty incompatible with the basic way the compiler parses the language. Not an issue in the curly brace languages, new-lines are just white space.

It has never been a real problem, Visual Basic has had strong IDE support for a very long time. Commenting out multiple lines is an IDE feature, Edit + Advanced + Comment Selection.

回答2:

Totally abusing compiler directives here... but:

#If False Then
Comments
go
here
#End If

You don't get the benefits of proper code coloration (it doesn't show in green when using the default color scheme) and the implicit line-continuation system automatically indents lines in a paragraph starting at the second line. But the compiler will ignore the text.

回答3:

As can be read in “Comments in Code“ there isn't any other way:

If your comment requires more than one line, use the comment symbol on each line, as the following example illustrates.

' This comment is too long to fit on a single line, so we break 
' it into two lines. Some comments might need three or more lines.

Similarly, the help on the REM statement states:

Note:
You cannot continue a REM statement by using a line-continuation sequence (_). Once a comment begins, the compiler does not examine the characters for special meaning. For a multiple-line comment, use another REM statement or a comment symbol (') on each line.

回答4:

Depending on how many lines are to be ignored, one can use compiler directives instead. It may not be technically equivalent to comments (you don't get the syntax coloring of comments, for example), but it gets the job done without commenting many lines individually. So you just add 3 more lines of code.

#Const COMMENT = "C"
'basically a false statement
#If COMMENT = "Y"  Then
   'code to be commented goes between #If and #End If
   MsgBox('Commenting failed!')
#End If

This is assuming the purpose is for ignoring blocks of code instead of adding documentation (what "comments" are actually used for, but I also wouldn't mind using compiler directives for that).

The effort required however, makes this method inconvenient when there are just around 10 lines to comment.

Reference: http://msdn.microsoft.com/en-us/library/tx6yas69.aspx