{"Entry":{"collection":"language","key":"pltcl","name":"pltcl","aliases":[],"metadata":{"aliases":[],"category":"PL/Tcl","content_hash":"41d652076c86662d737dae6716830b706fe534aa59c1dbe1476ddabfde05ea81","derived_content_hash":"ed341b2725ff6416ff8b92aabb96f5cebb559692cb679dc21e13bff60e2a1a98","imported_at":"2026-09-30T00:40:44.369471+08:00","name":"pltcl","name_zh":"","slug":"pltcl","summary":"PL/Tcl procedural language"}},"Definition":{"Collection":"language","Key":"pltcl","SourceDatabase":"center","Version":"18","SourceTable":"procedural_language","SourceKey":"pltcl","SourceRevision":"555610c24d53e4316da5b7d3fc25c279d96856d5e0e23ee308c328c5fa881d9f","Facts":{"aliases":[],"attributes":{"comment":"PL/Tcl procedural language","default_version":"1.0","family":"PL/Tcl","handler":"pltcl_call_handler","inline_handler":"","kind":"Bundled procedural-language variant","library":"$libdir/pltcl","module_pathname":"$libdir/pltcl","trusted":"t","validator":""},"comparison_data":{"default_version":"1.0","family":"PL/Tcl","handler":"pltcl_call_handler","inline_handler":"","kind":"Bundled procedural-language variant","library":"$libdir/pltcl","trusted":"t","validator":""},"comparison_hash":"e46eb0b37d7a8df979587d5efa5dc9dcdd895a8ee52bb73a51e62f5b705e3b47","description":["PL/Tcl procedural language"],"description_zh":"过程语言 pltcl。","description_zh_html":"\u003cp\u003e过程语言 pltcl。\u003c/p\u003e\u003cdl\u003e\u003cdt\u003e运算符族\u003c/dt\u003e\u003cdd\u003e\u003ccode\u003ePL/Tcl\u003c/code\u003e\u003c/dd\u003e\u003cdt\u003e处理函数\u003c/dt\u003e\u003cdd\u003e\u003ccode\u003epltcl_call_handler\u003c/code\u003e\u003c/dd\u003e\u003cdt\u003e库\u003c/dt\u003e\u003cdd\u003e\u003ccode\u003e$libdir/pltcl\u003c/code\u003e\u003c/dd\u003e\u003cdt\u003e受信任\u003c/dt\u003e\u003cdd\u003e\u003ccode\u003e是\u003c/code\u003e\u003c/dd\u003e\u003cdt\u003e默认版本\u003c/dt\u003e\u003cdd\u003e\u003ccode\u003e1.0\u003c/code\u003e\u003c/dd\u003e\u003cdt\u003e模块路径\u003c/dt\u003e\u003cdd\u003e\u003ccode\u003e$libdir/pltcl\u003c/code\u003e\u003c/dd\u003e\u003c/dl\u003e\u003ch3\u003e同版本中文手册节选\u003c/h3\u003e\u003cp\u003e\n    PL/Tcl 提供了函数编写者在 C 语言中所具备的大部分能力，但会施加少量限制，并额外提供 Tcl 可用的强大字符串处理库。\n   \u003c/p\u003e\u003cp\u003e\n    其中一个颇具吸引力的\u003cspan class=\"emphasis\"\u003e\u003cem\u003e良性\u003c/em\u003e\u003c/span\u003e限制是，所有内容都在 Tcl 解释器的安全上下文中执行。除了安全 Tcl 受限的命令集之外，只提供了少数通过 SPI 访问数据库以及通过 \u003ccode class=\"function\"\u003eelog()\u003c/code\u003e 发出消息的命令。与 C 函数不同，PL/Tcl 不提供访问数据库服务器内部机制的方法，也不能在 \u003cspan class=\"productname\"\u003ePostgreSQL\u003c/span\u003e 服务器进程的权限下获得操作系统级访问。因此，可以信任非特权数据库用户使用这种语言；它不会授予他们无限制的权限。\n   \u003c/p\u003e\u003cp\u003e\n    另一项值得注意的实现限制是，Tcl 函数不能用来为新数据类型创建输入/输出函数。\n   \u003c/p\u003e\u003cp\u003e\n    有时需要编写不受安全 Tcl 限制的 Tcl 函数。例如，可能希望某个 Tcl 函数能够发送电子邮件。为处理这类情况，\u003cspan class=\"application\"\u003ePL/Tcl\u003c/span\u003e 提供了一个名为 \u003ccode class=\"literal\"\u003ePL/TclU\u003c/code\u003e 的变体（其中 U 表示不受信任的 Tcl）。除了使用完整的 Tcl 解释器之外，它与前者是完全相同的语言。\u003cspan class=\"emphasis\"\u003e\u003cem\u003e如果使用 \u003cspan class=\"application\"\u003ePL/TclU\u003c/span\u003e，就必须将其安装为一种不受信任的过程语言\u003c/em\u003e\u003c/span\u003e，这样就只有数据库超级用户才能在其中创建函数。\u003cspan class=\"application\"\u003ePL/TclU\u003c/span\u003e 函数的编写者必须确保该函数不会被用来做任何不希望发生的事情，因为它能够执行任何以数据库管理员身份登录的用户所能做的事情。\n   \u003c/p\u003e\u003cp\u003e\u003ca href=\"/zh/docs/18/pltcl-overview.html\"\u003e查看完整中文手册与上下文\u003c/a\u003e。\u003c/p\u003e","facts":[{"label":"Kind","value":"Bundled procedural-language variant"},{"label":"Family","value":"PL/Tcl"},{"label":"Trusted","value":"t"},{"label":"Handler","value":"pltcl_call_handler"},{"label":"Library","value":"$libdir/pltcl"},{"label":"Default version","value":"1.0"},{"label":"Module pathname","value":"$libdir/pltcl"},{"label":"Comment","value":"PL/Tcl procedural language"}],"facts_zh":[{"label":"种类","value":"随源码提供的过程语言变体"},{"label":"操作符家族","value":"PL/Tcl"},{"label":"可信","value":"t"},{"label":"处理函数","value":"pltcl_call_handler"},{"label":"库","value":"$libdir/pltcl"},{"label":"默认版本","value":"1.0"},{"label":"模块路径","value":"$libdir/pltcl"},{"label":"注释","value":"PL/Tcl 过程语言"}],"manual_html":"\u003cdiv class=\"sect1\" id=\"PLTCL-OVERVIEW\"\u003e\n\u003cdiv class=\"titlepage\"\u003e\n\u003cdiv\u003e\n\u003cdiv\u003e\n\u003ch2 class=\"title\"\u003e42.1. Overview \u003c/h2\u003e\n\u003c/div\u003e\n\u003c/div\u003e\n\u003c/div\u003e\n\u003cp\u003ePL/Tcl offers most of the capabilities a function writer has in the C language, with a few restrictions, and with the addition of the powerful string processing libraries that are available for Tcl.\u003c/p\u003e\n\u003cp\u003eOne compelling \u003cspan class=\"emphasis\"\u003e\u003cem\u003egood\u003c/em\u003e\u003c/span\u003e restriction is that everything is executed from within the safety of the context of a Tcl interpreter. 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Its presence does not establish that the language or external runtime is installed."],"title":"Installation definition from the matching source archive"}],"tables":[]}},"RequestedLocale":"en","Fallback":false,"Versions":["10","11","12","13","14","15","16","17","18","19","20"],"Locales":["en","zh-Hans"],"Signatures":null,"Spellings":null,"SQLState":null,"Evidence":null}