Why isn't this string.match consistently worki

问题:

I am writing an addon for the game World of Warcraft (WoW). It uses lua, with a library of functions specific to the game. I am checking whether a substring can be found in a string. The substring in question is given by the variable ItemType, which in this case contains the string "Two-Handed Swords". The string in which I am checking is given by a table entry and contains "One-Handed Axes, One-Handed Swords, Two-Handed Axes, Two-Handed Swords, Bows, Crossbows, Guns, Wands, Mail, Plate, Shields". The problem is that when I run the function on the item in question, it's acting as if the item doesn't match.

The full code is as follows

local NotUsableItemsTable = {
    "Wands",
    "Daggers, Fist Weapons, Staves, Bows, Crossbows, Guns, Wands",
    "One-Handed Maces, Two-Handed Maces, Wands, Plate, Shields",
    "Polearms, Staves, Two-Handed Axes, Two-Handed Maces, Two-Handed Swords, Wands, Mail, Plate, Shields",
    "Fist Weapons, One-Handed Axes, One-Handed Swords, Polearms, Two-Handed Axes, Two-Handed Maces, Two-Handed Swords, Bows, Crossbows, Guns, Leather, Mail, Plate, Shields",
    "Daggers, Fist Weapons, Staves, Bows, Crossbows, Guns, Wands, Shields",
    "One-Handed Swords, Polearms, Two-Handed Swords, Bows, Crossbows, Guns, Wands, Plate",
    "Fist Weapons, One-Handed Axes, One-Handed Maces, Polearms, Two-Handed Axes, Two-Handed Maces, Two-Handed Swords, Bows, Crossbows, Guns, Leather, Mail, Plate, Shields",
    "Fist Weapons, One-Handed Axes, One-Handed Maces, Polearms, Two-Handed Axes, Two-Handed Maces, Two-Handed Swords, Bows Crossbows, Guns, Leather, Mail, Plate, Shields",
    "Placeholder String: There is no class corresponding to index 10.",
    "One-Handed Axes, One-Handed Swords, Two-Handed Axes, Two-Handed Swords, Bows, Crossbows, Guns, Wands, Mail, Plate, Shields"
}

function IsItemUseableByPlayer(itemID)
    if itemID == nil then return nil end
    local ClassInfo = {UnitClass("player")}
    local NotUsableItemsString = NotUsableItemsTable[ClassInfo[3]]
    local ItemInfo = {GetItemInfo(itemID)}
    local ItemType = ItemInfo[7]
    if string.match(NotUsableItemsString, ItemType) then
        return true
    else
        return false
    end
end

UnitClass("player") returns { "Druid", "DRUID", 11 } in this case. ItemType i.e. ItemInfo[7] returns "Two-Handed Swords"

回答1:

- is a magic character in Lua pattern matching. You need to escape it with a %.

You can also use string.find, which can be asked to do plain matching.

回答2:

Your strings contain characters with special meaning in Lua patterns, in this case the -. You have to escape it with %.