C# Rules

Design Guidelines for Developing Class Libraries

No.1

Keep classes size small.

Large class trying to do too many things.

Figure out responsibly, use delegation and collaborate small classes

No.2

Keep methods short.

Normally, 1-10 lines is ok, 10-20 lines is pushing it, may be need a quick check. 20-40 lines usually need to break.

Solution: divide it into methods.

No.3

Try to avoid comments, unless its for API documents.

If comments have any purpose, it will be relieve the tension of the code, try to explain the code function. In that case, I intend to refactor or abstract it to  method to self-explain.

No.4

Try to avoid multiple Exits

If we have single entry point, we should have single exit point.

use variable to hold return value, then return that variable at the end of the code.

No.5

Encapsulate complex expressions

The express may have lots of compare operation, like and, or, >,<. use method to encapsulate them, give it a meaningful name, return the compare result.

No.6

Treat warnings as Errors.

Use VS build-in function to force compile fails when there has a warning.

No.7

Avoid too man parameters.

Use class to wrap those parameters, too many parameters meaning there may have some connections between them and use class could provide some validation function

No.8

Avoid Boolean Parameters.

Why, because it may cause confusion in caller’s code. whenever someone invoke your API, there has a method with Boolean parameters, the reader doesn’t really know what’s that bool stands for, instead, rename the methods, provide multiple methods, will make your caller’s code much more cleaner.

No.9

Use Exceptions For Errors

Stop use boolean or status code for return value, if caller pass in some invalid parameters. Use exception could explicit tell caller what’s wrong, the cause of error may come from caller’s validation code. like check empty value of parameter.

No. 10

Avoid Use Regions

Generally, Regions are used to hide ugly code. Each of the region may could be a class, too many regions may meaning this class doing too many things.