TclOO 日志混合组件

huangapple
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英文:

TclOO Logging Mixin

问题

I wrote this code (below) trying to figure out more about TclOO mixin classes.

a. is there a more direct way to write the concrete class name from the mixin constructor?

使用mixin构造函数更直接的方法是否存在？

b. is there a way to simplify the mixin class using self requiring no additional calls (e.g. init) other than mixin (as below) when using it? (cross checked with https://stackoverflow.com/questions/50352363/tcloo-class-logger-mixin , not clear)

在使用mixin时，是否有一种方式可以简化mixin类，只使用self，而无需额外调用（例如init），如下所示？（与https://stackoverflow.com/questions/50352363/tcloo-class-logger-mixin进行了交叉检查，不清楚）

  1. package require TclOO
  2. package require try
  3. package require logger
  5. namespace eval ::demo::utils {}
  6. namespace eval ::demo::naming {}
  8. ::oo::class create ::demo::utils::LoggingMixin {
  9.     variable log
  11.     constructor {args} {
  12.         set concls [lindex [self call] 0 end end-1]
  13.         try {
  14.             set log [::logger::servicecmd $concls]
  15.         } trap {LOGGER NO_SUCH_SERVICE} {} {
  16.             set log [::logger::init $concls]
  17.         }
  19.         # check for next
  20.         if {[llength [self next]] > 0} {
  21.             next {*}$args
  22.         }
  23.     }
  24. }
  26. ::oo::class create ::demo::naming::GenericNaming {
  27.     mixin ::demo::utils::LoggingMixin
  29.     variable log
  31.     constructor {args} {
  32.         ${log}::info "hello world"
  33.     }
  34. }
  36. ::oo::class create ::demo::naming::NewNaming {
  37.     mixin ::demo::utils::LoggingMixin
  39.     variable log
  41.     constructor {args} {
  42.         ${log}::info "new world"
  43.     }
  44. }
  46. ::demo::naming::GenericNaming new
  48. ::demo::naming::NewNaming new

expected output:

  1. $ tclsh ./mixin.tcl  
  2. [Sun Jun 04 21:39:22 BST 2023] [::demo::naming::GenericNaming] [info] 'hello world'
  3. [Sun Jun 04 21:39:22 BST 2023] [::demo::naming::NewNaming] [info] 'new world'
英文:

I wrote this code (below) trying to figure out more about TclOO mixin classes.

a. is there a more direct way to write the concrete class name from the mixin constructor?

> set concls [lindex [self call] 0 end end-1]

b. is there a way to simplify the mixin class using self requiring no additional calls (e.g. init) other than mixin (as below) when using it? (cross checked with https://stackoverflow.com/questions/50352363/tcloo-class-logger-mixin , not clear)

> mixin ::demo::utils::LoggingMixin

  1. package require TclOO
  2. package require try
  3. package require logger
  5. namespace eval ::demo::utils {}
  6. namespace eval ::demo::naming {}
  8. ::oo::class create ::demo::utils::LoggingMixin {
  9.     variable log
  10.     
  11.     constructor {args} {
  12.         set concls [lindex [self call] 0 end end-1]
  13.         try {
  14.             set log [::logger::servicecmd $concls]
  15.         } trap {LOGGER NO_SUCH_SERVICE} {} {
  16.             set log [::logger::init $concls]
  17.         }
  19.         # check for next
  20.         if {[llength [self next]] > 0} {
  21.             next {*}$args
  22.         }
  23.     }
  24. }
  26. ::oo::class create ::demo::naming::GenericNaming {
  27.     mixin ::demo::utils::LoggingMixin
  28.     
  29.     variable log
  30.     
  31.     constructor {args} {
  32.         ${log}::info "hello world"
  33.     }
  34. }
  36. ::oo::class create ::demo::naming::NewNaming {
  37.     mixin ::demo::utils::LoggingMixin
  38.     
  39.     variable log
  40.     
  41.     constructor {args} {
  42.         ${log}::info "new world"
  43.     }
  45. }
  48. ::demo::naming::GenericNaming new
  50. ::demo::naming::NewNaming new

expected output:

  1. $ tclsh ./mixin.tcl  
  2. [Sun Jun 04 21:39:22 BST 2023] [::demo::naming::GenericNaming] [info] 'hello world'
  3. [Sun Jun 04 21:39:22 BST 2023] [::demo::naming::NewNaming] [info] 'new world'

答案1

得分: 3

获取正在创建的对象的类，只需在构造函数中执行以下操作：

  1. set concls [info object class [self]]

无需遍历参数（这很好，因为在存在复杂的转发或已覆盖new和/或create时，这样做会更容易出错）。

Tcl 8.6不需要您执行package require TclOO或package require try；这些都是内置功能。

我倾向于这样设置日志混合类：

  1. oo::class create ::demo::utils::LoggingMixin {
  2.     variable log
  3.     
  4.     constructor {args} {
  5.         set concls [info object class [self]]
  6.         try {
  7.             set log [::logger::servicecmd $concls]
  8.         } trap {LOGGER NO_SUCH_SERVICE} {} {
  9.             set log [::logger::init $concls]
  10.         }
  11.         next {*}$args
  12.     }
  14.     # TODO: 为其他所需的日志级别添加方法
  15.     method LogInfo args {
  16.         tailcall ${log}::info {*}$args
  17.     }
  18. }

因为然后子类可以只是这样的：

  1. oo::class create LoggingDemo {
  2.     mixin ::demo::utils::LoggingMixin
  3.     constructor {args} {
  4.         my LogInfo "new world"
  5.     }
  6. }

或者甚至可以制作一些过程来进一步改进语法：

  1. constructor {args} {
  2.     set concls [info object class [self]]
  3.     try {
  4.         set log [::logger::servicecmd $concls]
  5.     } trap {LOGGER NO_SUCH_SERVICE} {} {
  6.         set log [::logger::init $concls]
  7.     }
  8.     proc logInfo args {
  9.         variable log; # 需要明确指定这一点
  10.         tailcall ${log}::info {*}$args
  11.     }
  12.     next {*}$args
  13. }

另一种方法是使混合类提供自我初始化的日志方法：

  1. oo::class create ::demo::utils::LoggingMixin {
  2.     variable LoggingMixinLog
  3.     
  4.     method GetLog {level} {
  5.         if {![info exist LoggingMixinLog]} {
  6.             set concls [info object class [self]]
  7.             try {
  8.                 set LoggingMixinLog [::logger::servicecmd $concls]
  9.             } trap {LOGGER NO_SUCH_SERVICE} {} {
  10.                 set LoggingMixinLog [::logger::init $concls]
  11.             }
  12.         }
  13.         return ${LoggingMixinLog}::$level
  14.     }
  16.     method LogInfo args {
  17.         tailcall [my GetLog info] {*}$args
  18.     }
  19. }
  21. oo::class create LoggingDemo {
  22.     mixin ::demo::utils::LoggingMixin
  23.     constructor {args} {
  24.         my LogInfo "new world"
  25.     }
  26. }

这有助于在事后混合到对象或类中的支持。如果要创建日志包装器，建议使用tailcall或uplevel 1来调用它们，以便当前的堆栈帧是想要创建日志条目的堆栈帧，而不是小型代理帮助方法/过程。

英文:

To get the class of the object being created, it is sufficient to do this in the constructor:

  1. set concls [info object class [self]]

You don't need to pick through the arguments (good, as that's more error-prone when there are complex forwardings in place or new and/or create have been overridden).

Tcl 8.6 doesn't need you to package require TclOO or package require try; both are built-in features these days.

I'd be inclined to set up the logging mixin like this:

  1. oo::class create ::demo::utils::LoggingMixin {
  2.     variable log
  3.     
  4.     constructor {args} {
  5.         set concls [info object class [self]]
  6.         try {
  7.             set log [::logger::servicecmd $concls]
  8.         } trap {LOGGER NO_SUCH_SERVICE} {} {
  9.             set log [::logger::init $concls]
  10.         }
  11.         next {*}$args
  12.     }
  14.     # TODO: Add methods for other wanted logging levels
  15.     method LogInfo args {
  16.         tailcall ${log}::info {*}$args
  17.     }
  18. }

Because then the subclass could be just this:

  1. oo::class create LoggingDemo {
  2.     mixin ::demo::utils::LoggingMixin
  3.     constructor {args} {
  4.         my LogInfo "new world"
  5.     }
  6. }

Or I might even make some procedures to improve the syntax further:

  1.     constructor {args} {
  2.         set concls [info object class [self]]
  3.         try {
  4.             set log [::logger::servicecmd $concls]
  5.         } trap {LOGGER NO_SUCH_SERVICE} {} {
  6.             set log [::logger::init $concls]
  7.         }
  8.         proc logInfo args {
  9.             variable log; # Need to be explicit with this
  10.             tailcall ${log}::info {*}$args
  11.         }
  12.         next {*}$args
  13.     }

Another approach is to make the mixin provide logging methods that are self-initializing:

  1. oo::class create ::demo::utils::LoggingMixin {
  2.     variable LoggingMixinLog
  3.     
  4.     method GetLog {level} {
  5.         if {![info exist LoggingMixinLog]} {
  6.             set concls [info object class [self]]
  7.             try {
  8.                 set LoggingMixinLog [::logger::servicecmd $concls]
  9.             } trap {LOGGER NO_SUCH_SERVICE} {} {
  10.                 set LoggingMixinLog [::logger::init $concls]
  11.             }
  12.         }
  13.         return ${LoggingMixinLog}::$level
  14.     }
  16.     method LogInfo args {
  17.         tailcall [my GetLog info] {*}$args
  18.     }
  19. }
  21. oo::class create LoggingDemo {
  22.     mixin ::demo::utils::LoggingMixin
  23.     constructor {args} {
  24.         my LogInfo "new world"
  25.     }
  26. }

That has the advantage of supporting mixing into objects or classes after the fact.

If you make logging wrappers, calling them with either tailcall or uplevel 1 is advisable so that the current stack frame is the one that wants to make the log entry, not the little proxy helper method/procedure.

huangapple
  • 本文由 发表于 2023年6月5日 05:07:12
  • 转载请务必保留本文链接：https://go.coder-hub.com/76402415.html
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