The page I am working on has a javascript function executed to print parts of the page. For some reason, printing in Safari, causes the window to somehow update. I say somehow, because it does not really refresh as in reload the page, but rather it starts the "rendering" of the page from start, i.e. scroll to top, flash animations start from 0, and so forth. The effect is reproduced by this fiddle: http://jsfiddle.net/fYmnB/ Clicking the print button and finishing or cancelling a print in Safari causes the screen to "go white" for a sec, which in my real website manifests itself as something "like" a reload. While running print button with, let's say, Firefox, just opens and closes the print dialogue without affecting the fiddle page in any way. Is there something with my way of calling the browsers print method that causes this, or how can it be explained - and preferably, avoided? P.S.: On my real site the same occurs with Chrome. In the ex
PHP uses a single-pass compilation process in which it converts the source code into an opcode stream (which is then executed). Because the compilation uses only a single pass and does not build an AST most optimizations commonly done by other languages would be very hard to implement. There obviously are some simple optimizations done (like interning strings and prehashing symbols), but most of the "advanced" optimizations are simply not possible.
ReplyDeleteBy the way, a very simple way to "optimize" PHP code is to cache the generated opcode stream using the APC extension, so that it isn't recreated on every page load: The compilation process is quite resource intensive and using APC can often lower your CPU usage quite a bit.
PHP itself probably does some optimizations during interpretation, though I am not aware of any significant ones.
ReplyDeleteBut since PHP is extendable, a range of so-called PHP accelerators can be found around the web. An accelerator is a PHP extension which does some form of optimization for you, typically by employing opcode caching or similar.
Distinguishing between interpretation (what the standard PHP distribution does) and compilation, several PHP compilers are available. You can pass PHP code through a PHP compiler which (rather than interpreting and executing the code on the fly) builds an optimized executable format for you.