From 2e98c3d0644fc0c265844908f43b7e4526dd819c Mon Sep 17 00:00:00 2001 From: Mike Pall Date: Thu, 23 Jun 2022 09:10:09 +0200 Subject: Grammar and spell check. --- doc/ext_ffi_tutorial.html | 24 ++++++++++++------------ 1 file changed, 12 insertions(+), 12 deletions(-) (limited to 'doc/ext_ffi_tutorial.html') 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")

-Please note this doesn't define an ffi variable in the table +Please note, this doesn't define an ffi variable in the table of globals — you really need to use the local variable. The require function ensures the library is only loaded once.

@@ -190,7 +190,7 @@ don't need to declare them as such. ⑤ The poll() function takes a couple more arguments we're not going to use. You can simply use nil to pass a NULL pointer and 0 -for the nfds parameter. Please note that the +for the nfds parameter. Please note, that the number 0 does not convert to a pointer value, 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:

① 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.

② This loads the zlib shared -library. On POSIX systems it's named libz.so and usually +library. On POSIX systems, it's named libz.so and usually comes pre-installed. Since ffi.load() automatically adds any missing standard prefixes/suffixes, we can simply load the "z" library. On Windows it's named zlib1.dll and @@ -320,7 +320,7 @@ actual length that was used.

In C you'd pass in the address of a local variable (&buflen). 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 zlib.compress2 function is then straightforward.

@@ -344,7 +344,7 @@ for garbage collection and string interning. ⑥ The uncompress functions does the exact opposite of the compress 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.

⑦ The code, that makes use @@ -378,7 +378,7 @@ Ok, so the ffi.* functions generally accept cdata objects wherever you'd want to use a number. That's why we get a away with passing n to ffi.string() above. But other Lua library functions or modules don't know how to deal with this. So for -maximum portability one needs to use tonumber() on returned +maximum portability, one needs to use tonumber() on returned long 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.

④ If we run out of operators, we can -define named methods, too. Here the __index table defines an +define named methods, too. Here, the __index table defines an area function. For custom indexing needs, one might want to define __index and __newindex functions instead.

@@ -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.

-Please note that the association with a metatable is permanent and +Please note, that the association with a metatable is permanent and the metatable must not be modified afterwards! Ditto for the __index table.

⑥ 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 a.x) can be freely mixed with the newly defined metamethods. Note that area is a method and must be called with the Lua syntax for methods: a:area(), not @@ -479,7 +479,7 @@ called with the Lua syntax for methods: a:area(), not

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 __index to the library namespace and __gc to the destructor and you're done. But often enough you'll want to add @@ -565,7 +565,7 @@ end

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: 

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