template-variables | 易学教程

string.format() with optional placeholders

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问题 I have the following Python code (I'm using Python 2.7.X): my_csv = '{first},{middle},{last}' print( my_csv.format( first='John', last='Doe' ) ) I get a KeyError exception because 'middle' is not specified (this is expected). However, I want all of those placeholders to be optional. If those named parameters are not specified, I expect the placeholders to be removed. So the string printed above should be: John,,Doe Is there built in functionality to make those placeholders optional, or is

Does PHP have a feature like Python's template strings?

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问题 Python has a feature called template strings. >>> from string import Template >>> s = Template('$who likes $what') >>> s.substitute(who='tim', what='kung pao') 'tim likes kung pao' I know that PHP allows you to write: "Hello $person" and have $person substituted, but the templates can be reused in various sections of the code? 回答1: You could also use strtr: $template = '$who likes $what'; $vars = array( '$who' => 'tim', '$what' => 'kung pao', ); echo strtr($template, $vars); Outputs: tim

Templated Function Pointer Arrays in Visual Studio

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问题 Guillaume Racicot gave an excellent answer to this question on how I could specialize template variables. But I'm having trouble in visual-studio-2017 with creating a templated array of function pointers. This code for example: struct vec { double x; double y; double z; }; namespace details { template <typename T> constexpr double X(const T& param) { return param.x; } template <typename T> constexpr double Y(const T& param) { return param.y; } template <typename T> constexpr double Z(const T&

String interpolation in YAML

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In Perl I can do something like the following: my $home = "/home"; my $alice = "$home/alice"; Can I do something like the following in YAML: Home: /home Alice: $Home/alice So "Alice" is effectively /home/alice in the end? Paul Fioravanti Unfortunately, you're out of luck. To do what you want you'd need to pass in $home from a view file (or wherever) and interpolate it in your yaml entry, which could possibly look something like: Alice: ! '%{home}/Alice' See this StackOverflow Q&A for the detailed answer to pretty much exactly your question. You should use ERB template. you can write like

Use placeholders in yaml

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Is there a way to use placeholders in yaml like this: foo: &FOO <<propname>>: type: number default: <<default>> bar: - *FOO propname: "some_prop" default: "some default" Context YAML version 1.2 user wishes to include variable placeholders in YAML Problem YAML does not natively support variable placeholders Anchors and Aliases do allow for some level of abstraction and indirection, but these do not work as variable placeholders that can be inserted into arbitrary regions throughout the YAML text. They must be placed as separate YAML nodes There are some add-on libraries that support arbitrary

Use placeholders in yaml

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问题 Is there a way to use placeholders in yaml like this: foo: &FOO <<propname>>: type: number default: <<default>> bar: - *FOO propname: \"some_prop\" default: \"some default\" 回答1: Context YAML version 1.2 user wishes to include variable placeholders in YAML have placeholders replaced with computed values, upon yaml.load be able to use placeholders for both YAML mapping keys and values Problem YAML does not natively support variable placeholders Anchors and Aliases do allow for some level of