【机器视觉】 global算子

妖狐艹你老母 2022-10-07 05:51 224阅读 0赞

## 00. 目录 ##

### 文章目录 ###

*   *  00. 目录
     *  01. 概述
     *  02. 签名
     *  03. 描述
     *  04. 注意
     *  05. 参数
     *  06. 结果
     *  07. 附录

## 01. 概述 ##

global - 声明一个全局变量。

## 02. 签名 ##

`global( : : Declaration : )`

## 03. 描述 ##

可以用来声明一个全局变量。 声明的全局变量对所有其他程序也是可见的，所有其他程序也需要显式声明与全局变量相同的变量。

如果某个变量没有在程序中显式声明为全局变量，则即使存在具有相同名称的全局变量，该变量也是该程序中的局部变量。

参数Declaration 由可选关键字’def’，类型’object’或’tuple’，可选关键字’vector’（后接圆括号中的所需维度）和变量名组成的变量声明等部分组成。

声明一个图型变量的类型为’object’，声明一个控制变量为’tuple’。

关键字’def’将一个声明显式标记为变量被定义的地方。 在大多数情况下，这不是必须的，因为在HDevelop中，变量实例只要在某个地方被声明就立即创建。 但是，如果将多个程序导出为编程语言，并且如果这些程序不是导出到一个包含所有程序的输出文件中，而是导出到单独的输出文件中，标记全局变量定义的位置是必须的。 链接（引用）到一个库或应用程序的一组程序导出文件必须包含每个全局变量的一个定义，以避免符号未定义和多次定义。

在程序列表中，全局变量声明需要显示，并且必须不能输入括号，以强调该行是声明而不是可执行的算子。 语法如下：

global \[def\] \{object|tuple\} \[vector()\]

**原文描述**：

The global statement can be used to declare a global variable. By declaring a variable as global the variable becomes visible to all other procedures that also declare the same variable explicitly as global.

If a variable is not explicitly declared as global inside a procedure, the variable is local within that procedure even if there is a global variable with the same name.

The parameter Declaration contains the variable declaration that consists of the optional keyword ‘def’, the type ‘object’ or ‘tuple’, the optional keyword ‘vector’ (followed by the desired dimension in round brackets), and the variable name.

Setting the type to ‘object’ an iconic variable is declared, by setting it to ‘tuple’ a control variable is declared.

The keyword ‘def’ allows to mark one declaration explicitly as the place where the variable is defined. In most cases this will not be necessary because in HDevelop the variable instance is created as soon as it is declared somewhere. However, if several procedures are exported to a programming language and if the procedures are not exported into one output file that contains all procedures together but into separate output files it will become necessary to mark one of the global variable declarations as the place where the variable is defined. A set of procedure export files that are linked to one library or application must contain exactly one definition of each global variable in order to avoid both undefined symbols and multiple definitions.

In the program listing, global variable declarations are displayed and must be entered without parenthesis in order to emphasize that the line is a declaration and not an executable operator. The syntax is as follows:

global \[def\] \{object|tuple\} \[vector()\]

## 04. 注意 ##

略

## 05. 参数 ##

Declaration (input\_control) 　　string → (string)  
全局变量声明：可选关键字’def’，类型和变量名称  
推荐值: ‘object’, ‘tuple’, ‘def object’, ‘def tuple’, ‘object vector(1)’, ‘tuple vector(1)’, ‘def object vector(1)’, ‘def tuple vector(1)’

## 06. 结果 ##

global不会执行。

**HDevelop例程**  
variable\_types.hdev Define variable types in HDevelop

## 07. 附录 ##

**7.1 机器视觉博客汇总**  
网址：[https://dengjin.blog.csdn.net/article/details/116837497][https_dengjin.blog.csdn.net_article_details_116837497]

[https_dengjin.blog.csdn.net_article_details_116837497]: https://dengjin.blog.csdn.net/article/details/116837497