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Overview
Comment: | Added more info on quoting rules in Tcl/TH1 to the th1.md doc |
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Downloads: | Tarball | ZIP archive |
Timelines: | family | ancestors | descendants | both | trunk |
Files: | files | file ages | folders |
SHA3-256: |
30e9ccd59dda6c2f332ef254f2c908fd |
User & Date: | wyoung 2018-09-04 12:10:18.151 |
Context
2018-09-05
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15:16 | Avoid column breaks inside a top-level bullet in the /sitemap. ... (check-in: dc5e06ff user: drh tags: trunk) | |
2018-09-04
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12:10 | Added more info on quoting rules in Tcl/TH1 to the th1.md doc ... (check-in: 30e9ccd5 user: wyoung tags: trunk) | |
11:59 | Fixed some grammar and spelling in the th1.md doc. ... (check-in: 40787f50 user: wyoung tags: trunk) | |
Changes
Changes to www/th1.md.
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72 73 74 75 76 77 78 79 80 81 82 83 84 85 | as an expression, and if that expression is true, evaluates its second argument (the third token) as a TH1 script. If the expression is false and the third argument is `else`, then the fourth argument is evaluated as a TH1 expression. So, you see, even though the example above spans five lines, it is really just a single command. Summary of Core TH1 Commands ---------------------------- The original Tcl language after when TH1 is modeled has a very rich repertoire of commands. TH1, as it is designed to be minimalist and embedded has a greatly reduced command set. The following bullets | > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > | 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 | as an expression, and if that expression is true, evaluates its second argument (the third token) as a TH1 script. If the expression is false and the third argument is `else`, then the fourth argument is evaluated as a TH1 expression. So, you see, even though the example above spans five lines, it is really just a single command. All of this also explains the emphasis on *unescaped* characters above: the curly braces `{ }` are string quoting characters in Tcl/TH1, not block delimiters as in C. This is how we can have a command that extends over multiple lines. It is also why the `else` keyword must be cuddled up with the closing brace for the `if` clause's scriptlet. The following is invalid Tcl/TH1: if {$current eq "dev"} { puts "hello" } else { puts "world" } If you try to run this under either Tcl or TH1, the interpreter will tell you that there is no `else` command, because with the newline on the third line, you terminated the `if` command. Occasionally in Tcl/TH1 scripts, you may need to use a backslash at the end of a line to allow a command to extend over multiple lines without being considered two separate commands. Here's an example from one of Fossil's test scripts: return [lindex [regexp -line -inline -nocase -- \ {^uuid:\s+([0-9A-F]{40}) } [eval [getFossilCommand \ $repository "" info trunk]]] end] Those backslashes allow the command to wrap nicely within a standard terminal width while telling the interpreter to consider those three lines as a single command. Summary of Core TH1 Commands ---------------------------- The original Tcl language after when TH1 is modeled has a very rich repertoire of commands. TH1, as it is designed to be minimalist and embedded has a greatly reduced command set. The following bullets |
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