diff options
Diffstat (limited to 'doc/ext_ffi_tutorial.html')
| -rw-r--r-- | doc/ext_ffi_tutorial.html | 24 |
1 files changed, 12 insertions, 12 deletions
diff --git a/doc/ext_ffi_tutorial.html b/doc/ext_ffi_tutorial.html index c5e423b8..de6b6f5e 100644 --- a/doc/ext_ffi_tutorial.html +++ b/doc/ext_ffi_tutorial.html @@ -81,7 +81,7 @@ of its functions: local ffi = require("ffi") </pre> <p> -Please note this doesn't define an <tt>ffi</tt> variable in the table +Please note, this doesn't define an <tt>ffi</tt> variable in the table of globals — you really need to use the local variable. The <tt>require</tt> function ensures the library is only loaded once. </p> @@ -190,7 +190,7 @@ don't need to declare them as such. <span class="mark">⑤</span> The <tt>poll()</tt> function takes a couple more arguments we're not going to use. You can simply use <tt>nil</tt> to pass a <tt>NULL</tt> pointer and <tt>0</tt> -for the <tt>nfds</tt> parameter. Please note that the +for the <tt>nfds</tt> parameter. Please note, that the number <tt>0</tt> <em>does not convert to a pointer value</em>, unlike in C++. You really have to pass pointers to pointer arguments and numbers to number arguments. @@ -287,12 +287,12 @@ Here's the step-by-step explanation: <p> <span class="mark">①</span> This defines some of the C functions provided by zlib. For the sake of this example, some -type indirections have been reduced and it uses the pre-defined +type indirections have been reduced and it uses the predefined fixed-size integer types, while still adhering to the zlib API/ABI. </p> <p> <span class="mark">②</span> This loads the zlib shared -library. On POSIX systems it's named <tt>libz.so</tt> and usually +library. On POSIX systems, it's named <tt>libz.so</tt> and usually comes pre-installed. Since <tt>ffi.load()</tt> automatically adds any missing standard prefixes/suffixes, we can simply load the <tt>"z"</tt> library. On Windows it's named <tt>zlib1.dll</tt> and @@ -320,7 +320,7 @@ actual length that was used. <p> In C you'd pass in the address of a local variable (<tt>&buflen</tt>). But since there's no address-of operator in -Lua, we'll just pass in a one-element array. Conveniently it can be +Lua, we'll just pass in a one-element array. Conveniently, it can be initialized with the maximum buffer size in one step. Calling the actual <tt>zlib.compress2</tt> function is then straightforward. </p> @@ -344,7 +344,7 @@ for garbage collection and string interning. <span class="mark">⑥</span> The <tt>uncompress</tt> functions does the exact opposite of the <tt>compress</tt> function. The compressed data doesn't include the size of the original string, -so this needs to be passed in. Otherwise no surprises here. +so this needs to be passed in. Otherwise, no surprises here. </p> <p> <span class="mark">⑦</span> The code, that makes use @@ -378,7 +378,7 @@ Ok, so the <tt>ffi.*</tt> functions generally accept cdata objects wherever you'd want to use a number. That's why we get a away with passing <tt>n</tt> to <tt>ffi.string()</tt> above. But other Lua library functions or modules don't know how to deal with this. So for -maximum portability one needs to use <tt>tonumber()</tt> on returned +maximum portability, one needs to use <tt>tonumber()</tt> on returned <tt>long</tt> results before passing them on. Otherwise the application might work on some systems, but would fail in a POSIX/x64 environment. @@ -450,7 +450,7 @@ the origin. </p> <p> <span class="mark">④</span> If we run out of operators, we can -define named methods, too. Here the <tt>__index</tt> table defines an +define named methods, too. Here, the <tt>__index</tt> table defines an <tt>area</tt> function. For custom indexing needs, one might want to define <tt>__index</tt> and <tt>__newindex</tt> <em>functions</em> instead. </p> @@ -464,13 +464,13 @@ be used e.g. to create an array of points. The metamethods automatically apply to any and all uses of this type. </p> <p> -Please note that the association with a metatable is permanent and +Please note, that the association with a metatable is permanent and <b>the metatable must not be modified afterwards!</b> Ditto for the <tt>__index</tt> table. </p> <p> <span class="mark">⑥</span> Here are some simple usage examples -for the point type and their expected results. The pre-defined +for the point type and their expected results. The predefined operations (such as <tt>a.x</tt>) can be freely mixed with the newly defined metamethods. Note that <tt>area</tt> is a method and must be called with the Lua syntax for methods: <tt>a:area()</tt>, not @@ -479,7 +479,7 @@ called with the Lua syntax for methods: <tt>a:area()</tt>, not <p> The C type metamethod mechanism is most useful when used in conjunction with C libraries that are written in an object-oriented -style. Creators return a pointer to a new instance and methods take an +style. Creators return a pointer to a new instance, and methods take an instance pointer as the first argument. Sometimes you can just point <tt>__index</tt> to the library namespace and <tt>__gc</tt> to the destructor and you're done. But often enough you'll want to add @@ -565,7 +565,7 @@ end </pre> <p> This turns them into indirect calls and generates bigger and slower -machine code. Instead you'll want to cache the namespace itself and +machine code. Instead, you'll want to cache the namespace itself and rely on the JIT compiler to eliminate the lookups: </p> <pre class="code"> |