RE: Delimiters for String Templates (the ultimate Bike Shed!)

Thinking about the desire to optimize for creating XML, HTML, JSON, and CSS, I realized that there are a variety of JavaScript libraries designed to do just that:

http://mustache.github.io/
http://www.dustjs.com/
http://handlebarsjs.com/
https://github.com/Mrdigs/Interpose.js

Several of these delimit expressions in string content with "{{" and "}}". Suppose we think very much in-the-box, using syntax that others have used for this purpose.  Although "{{" and "}}" can easily occur with nested JSON objects, it's easy enough to either add whitespace ("{ {") or embed the "{{" as a string if you just can't stand using whitespace in JSON objects.

So I would like to add the following possibility to the list:

5. <<< ... >>> and {{ ... }}


Let me apply this to a standard Mustache example.  In Mustache syntax, 
this is a template with a conditional section:

Hello {{name}}
You have just won {{value}} dollars!
{{#in_ca}}
Well, {{taxed_value}} dollars, after taxes.
{{/in_ca}}

In Mustache, a JSON object is supplied to provide the values of variables:

{
  "name": "Chris",
  "value": 10000,
  "taxed_value": 10000 - (10000 * 0.4),
  "in_ca": true
}

When rendered, this results in the following string:

Hello Chris
You have just won 10000 dollars!
Well, 6000.0 dollars, after taxes.

Assuming that the variable $a has been bound to the object shown above, here is the XQuery string template using Syntax #5:

<<<Hello {{$a.name}}
You have just won {{$a.value}} dollars!
{{ 
   if ($a.in_ca) 
   then <<<Well, {{$a.taxed_value}} dollars, after taxes.>>>
   else ""
}}>>>

Here's what it looks like embedded in a function:

declare function local:prize-message($a) as xs:string
{
<<< 
  <div>
    <h1>Hello {{$a.name}}</h1>
    <p>You have just won {{$a.value}} dollars!</p>
    {{ 
      if ($a.in_ca) 
      then <<< <p>Well, {{$a.taxed_value}} dollars, after taxes.</p> >>>
      else ""
    }}
  </div>
>>>
}

Here's what it looks like if we produce HTML instead of text:

declare function local:prize-message($a) as xs:string
{
<<<
  <div>
    <h1>Hello {{$a.name}}</h1>
    <p>You have just won {{$a.value}} dollars!</p>
    {{ 
      if ($a.in_ca) 
      then <<< <p>Well, {{$a.taxed_value}} dollars, after taxes.</p> >>>
      else ""
    }}
  </div>
>>>
}

Here's what it looks like if we produce JSON:

declare function local:prize-message($a) as xs:string
{
<<<
 { 
     "greetings" : "Hello!",
     "value" : $a.value
     {{
      if ($a.in_ca) 
      then 
<<<, 
    "taxed_value", {{ $a.taxed_value }}
>>>  
      else ""  
     }}
 }
>>> 
} 

Let's compare that to the other four syntaxes using the same functions:


### 1.  <<[ ... ]>>  and <<{ ... }>>

declare function local:prize-message($a) as xs:string
{
<<[ 
  <div>
    <h1>Hello <{$a.name}></h1>
    <p>You have just won <{$a.value}> dollars!</p>
    <{ 
      if ($a.in_ca) 
      then <<[ <p>Well, <{$a.taxed_value}> dollars, after taxes.</p> ]>>
      else ""
    }>
  </div>
]>>
}

Here's what it looks like if we produce HTML instead of text:

declare function local:prize-message($a) as xs:string
{
<<[
  <div>
    <h1>Hello <{$a.name}></h1>
    <p>You have just won <{$a.value}> dollars!</p>
    <{ 
      if ($a.in_ca) 
      then <<[ <p>Well, <{$a.taxed_value}> dollars, after taxes.</p> ]>>
      else ""
    }>
  </div>
]>>
}

Here's what it looks like if we produce JSON:

declare function local:prize-message($a) as xs:string
{
<<[
 { 
     "greetings" : "Hello!",
     "value" : $a.value
     <{
      if ($a.in_ca) 
      then 
<<[, 
    "taxed_value", <{ $a.taxed_value }>
]>>  
      else ""  
     }>
 }
]>> 
} 


### 2.   <[ ... ]>   and  <{ ... }>

declare function local:prize-message($a) as xs:string
{
<[ 
  <div>
    <h1>Hello <{$a.name}></h1>
    <p>You have just won <{$a.value}> dollars!</p>
    <{ 
      if ($a.in_ca) 
      then <[ <p>Well, <{$a.taxed_value}> dollars, after taxes.</p> ]>
      else ""
    }>
  </div>
]>
}

Here's what it looks like if we produce HTML instead of text:

declare function local:prize-message($a) as xs:string
{
<[
  <div>
    <h1>Hello <{$a.name}></h1>
    <p>You have just won <{$a.value}> dollars!</p>
    <{ 
      if ($a.in_ca) 
      then <[ <p>Well, <{$a.taxed_value}> dollars, after taxes.</p> ]>
      else ""
    }>
  </div>
]>
}

Here's what it looks like if we produce JSON:

declare function local:prize-message($a) as xs:string
{
<[
 { 
     "greetings" : "Hello!",
     "value" : $a.value
     <{
      if ($a.in_ca) 
      then 
<[, 
    "taxed_value", <{ $a.taxed_value }>
]>  
      else ""  
     }>
 }
]> 
} 


### 3.  @@[ ... ]@@  and @@{ ... }@@

declare function local:prize-message($a) as xs:string
{
@@[ 
  <div>
    <h1>Hello @@{$a.name}@@</h1>
    <p>You have just won @@{$a.value}@@ dollars!</p>
    @@{ 
      if ($a.in_ca) 
      then @@[ <p>Well, @@{$a.taxed_value}@@ dollars, after taxes.</p> ]@@
      else ""
    }@@
  </div>
]@@
}

Here's what it looks like if we produce HTML instead of text:

declare function local:prize-message($a) as xs:string
{
@@[
  <div>
    <h1>Hello @@{$a.name}@@</h1>
    <p>You have just won @@{$a.value}@@ dollars!</p>
    @@{ 
      if ($a.in_ca) 
      then @@[ <p>Well, @@{$a.taxed_value}@@ dollars, after taxes.</p> ]@@
      else ""
    }@@
  </div>
]@@
}

Here's what it looks like if we produce JSON:

declare function local:prize-message($a) as xs:string
{
@@[
 { 
     "greetings" : "Hello!",
     "value" : $a.value
     @@{
      if ($a.in_ca) 
      then 
@@[, 
    "taxed_value", @@{ $a.taxed_value }}
]@@  
      else ""  
     }}
 }
]@@ 
} 


### 4.   <[" ... "]> and <{ ... }> 

declare function local:prize-message($a) as xs:string
{
<[" 
  <div>
    <h1>Hello <{$a.name}></h1>
    <p>You have just won <{$a.value}> dollars!</p>
    <{ 
      if ($a.in_ca) 
      then <[" <p>Well, <{$a.taxed_value}> dollars, after taxes.</p> "]>
      else ""
    }>
  </div>
"]>
}

Here's what it looks like if we produce HTML instead of text:

declare function local:prize-message($a) as xs:string
{
<["
  <div>
    <h1>Hello <{$a.name}></h1>
    <p>You have just won <{$a.value}> dollars!</p>
    <{ 
      if ($a.in_ca) 
      then <[" <p>Well, <{$a.taxed_value}> dollars, after taxes.</p> "]>
      else ""
    }>
  </div>
"]>
}

Here's what it looks like if we produce JSON:

declare function local:prize-message($a) as xs:string
{
<["
 { 
     "greetings" : "Hello!",
     "value" : $a.value
     <{
      if ($a.in_ca) 
      then 
<[", 
    "taxed_value", <{ $a.taxed_value }>
"]>  
      else ""  
     }>
 }
"]> 
}

Received on Tuesday, 22 September 2015 21:19:36 UTC