I'm reading Steven N. S. Cheung 's "Economic Explanation" (2001). In vol 2 ch 2 section 2, he mentions Comparative Cost, or "the law of comparative advantage".
after quoting the britain/spain clothes/wine example of D. Ricardo, he says,
... each country has its own comparative advantage, however, this presumes barter or same currency. If there're different currencies and the exchange rate is regulated, in some situation the so-called "Purchasing Power Parity" would not work. ... for example during the 1997 Asian Financial Crisis, almost all Asian countries' currencies depreciated, while HKD was tied to USD, so Hong Kong lost quite some Comparative advantage.
What I don't get is, why currency exchange rate regulation would disable the comparative advantage? Currencies are just agent of trading, exchange rate won't disable the comparative advantage, so exchange rate change shall also not disable it, right?