Effective Go 学习笔记

• Every package should have a package comment, a block comment preceding the package clause.
  
  
• Every exported (capitalized) name in a program should have a doc comment.
  
  
• 在 Windows 的控制台里，可以用 findstr 来代替 Linux 下的 grep, 例如

  $ godoc regexp | grep parse

  可以用以下命令代替

  $ godoc regexp | findstr parse

• By convention, packages are given lower case, single-word names; there should be no need for underscores or mixedCaps.
  
  
• Call your string-converter method String not ToString.
  
  
• For strings, the range does more work for you, breaking out individual Unicode code points by parsing the UTF-8. Erroneous encodings consume one byte and produce the replacement rune U+FFFD.
  
  
• It's therefore possible—and idiomatic—to write an if-else-if-else chain as a switch.


• new(T) allocates zeroed storage for a new item of type T and returns its address, a value of type *T. In Go terminology, it returns a pointer to a newly allocated zero value of type T.
  

  p := new(SyncedBuffer)  // type *SyncedBuffer
  var v SyncedBuffer      // type  SyncedBuffer

• make(T, args) applies only to maps, slices and channels and does not return a pointer.
  
  
• If the slices might grow or shrink, they should be allocated independently to avoid overwriting the next line; if not, it can be more efficient to allocate a single array and point the individual slices into it.
  
  
• You can use the catchall format %v (for “value”); the result is exactly what Print and Println would produce.
  
  
•  It's a common and easy mistake to make, as this example shows.
  

  type MyString string
  func (m MyString) String() string {
      return fmt.Sprintf("MyString=%s", m) // Error: will recur forever.
  }
  

  It's also easy to fix: convert the argument to the basic string type, which does not have the method.

  type MyString string
  func (m MyString) String() string {
      return fmt.Sprintf("MyString=%s", string(m)) // OK: note conversion.
  }

• iota constant generator https://golang.org/ref/spec#Iota, https://github.com/golang/go/wiki/Iota
  
  
• The use of Sprintf to implement ByteSize's String method is safe because it calls Sprintf with %f, which is not a string format: Sprintf will only call the String method when it wants a string, and %f wants a floating-point value.
  
  
• init() is called after all the variable declarations in the package have evaluated their initializers.
  
  
• The rule about pointers vs. values for receivers is that value methods can be invoked on pointers and values, but pointer methods can only be invoked on pointers.
  
  
• It's an idiom in Go programs to convert the type of an expression to access a different set of methods.
  
  
• Since we can define a method for any type except pointers and interfaces, we can write a method for a function.
  
  
• Always check error returns; they're provided for a reason.
  
  
• When a program is under active development, the blank identifier provides a workaround.
  

  var _ = fmt.Printf // For debugging; delete when done.
  var _ io.Reader    // For debugging; delete when done.
  // TODO: use fd.
  _ = fd

  
  
  
• To import the package only for its side effects, rename the package to the blank identifier:
  

  import _ "net/http/pprof"
  

  
  
  
• Only interfaces can be embedded within interfaces.
  
  
• Do not share memory, instead, communicate.

  Do not communicate by sharing memory; instead, share memory by communicating.

  
  
  
• In Go, function literals are closures.
  
  
• Receivers always block until there is data to receive, if the channel is unbuffered.
  (read more: http://www.cnblogs.com/ahui2017/p/6662401.html)
  
  
• deferred functions can modify named return values. 
  
  
•  the error method (because it's a method bound to a type, it's fine, even natural, for it to have the same name as the builtin error type).