Comments on: Be Careful With the var Keyword and Expression Builders http://elegantcode.com/2009/03/21/be-careful-with-the-var-keyword-and-expression-builders/?utm_source=rss&utm_medium=rss&utm_campaign=be-careful-with-the-var-keyword-and-expression-builders Sun, 12 Feb 2012 18:54:00 +0000 hourly 1 http://wordpress.org/?v=3.0.5 By: Progressive Interfaces | Elegant Code http://elegantcode.com/2009/03/21/be-careful-with-the-var-keyword-and-expression-builders/comment-page-1/#comment-46643 Progressive Interfaces | Elegant Code Tue, 02 Jun 2009 21:38:16 +0000 http://elegantcode.com/2009/03/21/be-careful-with-the-var-keyword-and-expression-builders/#comment-46643 [...] Let’s start by showing a ‘traditional’ expression builder like the one I provided in my previous post: [...] [...] Let’s start by showing a ‘traditional’ expression builder like the one I provided in my previous post: [...]

]]> By: Experimenting With Fluent Interfaces in the Domain | Elegant Code http://elegantcode.com/2009/03/21/be-careful-with-the-var-keyword-and-expression-builders/comment-page-1/#comment-44979 Experimenting With Fluent Interfaces in the Domain | Elegant Code Sat, 28 Mar 2009 23:49:09 +0000 http://elegantcode.com/2009/03/21/be-careful-with-the-var-keyword-and-expression-builders/#comment-44979 [...] you might have guessed from my previous two blog posts, I’ve been experimenting with fluent interfaces lately. I’ve been [...] [...] you might have guessed from my previous two blog posts, I’ve been experimenting with fluent interfaces lately. I’ve been [...]

]]> By: Jan Van Ryswyck http://elegantcode.com/2009/03/21/be-careful-with-the-var-keyword-and-expression-builders/comment-page-1/#comment-44843 Jan Van Ryswyck Mon, 23 Mar 2009 19:43:03 +0000 http://elegantcode.com/2009/03/21/be-careful-with-the-var-keyword-and-expression-builders/#comment-44843 @rich: I'm not calling it an expression builder, but Martin Fowler is: http://martinfowler.com/dslwip/ExpressionBuilder.html @rich: I’m not calling it an expression builder, but Martin Fowler is:
http://martinfowler.com/dslwip/ExpressionBuilder.html

]]> By: Rich http://elegantcode.com/2009/03/21/be-careful-with-the-var-keyword-and-expression-builders/comment-page-1/#comment-44840 Rich Mon, 23 Mar 2009 16:00:07 +0000 http://elegantcode.com/2009/03/21/be-careful-with-the-var-keyword-and-expression-builders/#comment-44840 Hmm, the code provided makes perfect sense to me. I can't see how in the initial "expression builder" statement would ever assume that you were looking for an instance of the Product class. There may be an implicit operator to cast a ProductBuilder as a Product, but the compiler can't assume that's what you're trying to do. The implicit operator means that you can cast a ProductBuilder to a Product, but not that you must. The var keyword gets a type for that statement, and no more. Now, if your first var statement ended with a call to Build() (which might as well be public, given the implicit cast) then the var would easily know it should be a Product and not a ProductBuilder. Also, be careful with the use of the term "Expression Builder" when referring to .NET 3.0, especially when referring to the keyword "var". I was hoping to see some LINQ code in here or the building of an Expression tree, like Charlie describes here: http://blogs.msdn.com/charlie/archive/2008/01/31/expression-tree-basics.aspx Hmm, the code provided makes perfect sense to me. I can’t see how in the initial “expression builder” statement would ever assume that you were looking for an instance of the Product class. There may be an implicit operator to cast a ProductBuilder as a Product, but the compiler can’t assume that’s what you’re trying to do. The implicit operator means that you can cast a ProductBuilder to a Product, but not that you must. The var keyword gets a type for that statement, and no more. Now, if your first var statement ended with a call to Build() (which might as well be public, given the implicit cast) then the var would easily know it should be a Product and not a ProductBuilder.

Also, be careful with the use of the term “Expression Builder” when referring to .NET 3.0, especially when referring to the keyword “var”. I was hoping to see some LINQ code in here or the building of an Expression tree, like Charlie describes here: http://blogs.msdn.com/charlie/archive/2008/01/31/expression-tree-basics.aspx

]]> By: Dew Drop - Weekend Edition - March 21-22, 2009 | Alvin Ashcraft's Morning Dew http://elegantcode.com/2009/03/21/be-careful-with-the-var-keyword-and-expression-builders/comment-page-1/#comment-44795 Dew Drop - Weekend Edition - March 21-22, 2009 | Alvin Ashcraft's Morning Dew Sun, 22 Mar 2009 12:37:37 +0000 http://elegantcode.com/2009/03/21/be-careful-with-the-var-keyword-and-expression-builders/#comment-44795 [...] Be Careful With the var Keyword and Expression Builders (Jan Van Ryswyck) [...] [...] Be Careful With the var Keyword and Expression Builders (Jan Van Ryswyck) [...]

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